Hebrews 1:8 NASB 1995
But of the Son He says, “YOUR THRONE, O GOD, IS FOREVER AND EVER, AND THE RIGHTEOUS SCEPTER IS THE SCEPTER OF HIS KINGDOM.
Who is this "HIS" if the Father is speaking to the son?
Hebrews 1:8 NASB 1995
But of the Son He says, “YOUR THRONE, O GOD, IS FOREVER AND EVER, AND THE RIGHTEOUS SCEPTER IS THE SCEPTER OF HIS KINGDOM.
Who is this "HIS" if the Father is speaking to the son?
This is a serious textual problem, the reason why diverse mss has "your" is maybe it seems more reasonable and natural. Perhaps the scribes changed it from an unusual reading, and the "his" from the oldest few mss viz., Sinaiticus, Vaticanus and P46 (the oldest, but only three witnesses) may be accurate if we consider the criteria of uncomfortable readings as preferable. As the scribes are less likely to change it to the uncomfortable one. It is possible the author shifted to third person in the second part of the verse.
We should note that the scribes often altered the text to conform to the Septuagint reading, as we see even in verse 12 the phrase "like a garment" is removed to conform to the corresponding Psalm 102:26 quotation, in the latter and most witnesses, according to Metzger. Since it is acceptable to choose the easier reading verse 8 (your instead of his) as it doesn't change the meaning. There is nothing wrong if we do such minor conjectural alterations to improve readability even if we have to change the original text. However, changing from the narration to second person to third still makes it a confusing reading.
It is also possible that the oldest mss reading "his" is a scribal interpolation, as he interpreted the phrase "Your throne O God" as predicate nominative, and found the deity reference to the Son objectionable, as modern Unitarians do. The critical Greek NT and all English versions therefore go with "your" instead of "his", since that is a widespread well attested reading. This view is more plausible, and it fits better with the internal passage as well as Metzger mentions in his textual commentary:
Although the reading auvtou/, which has early and good support (p46 א B), may seem to be preferable because it differs from the reading of the Old Testament passage that is being quoted (Ps 45.7 [= LXX 44:7] sou your), to which, on this point of view, presumably the mass of New Testament witnesses have been assimilated, a majority of the Committee was more impressed (a) by the weight and variety of the external evidence supporting sou, and (b) by the internal difficulty of construing auvtou/. Thus, if one reads auvtou/ the words ό θεός must be taken, not as a vocative4 (an interpretation that is preferred by most exegetes), but as the subject (or predicate nominative),5 an interpretation that is generally regarded as highly improbable. Even if one assumes that kai,, which is absent from the Hebrew and the Septuagint of the Psalm, was inserted by the author with the set purpose of making two separate quotations, with ver. 8a in the second person and 8b in the third person,6 the strangeness of the shift in persons is only slightly reduced.
4 “Thy throne, O God, is for ever and ever, and the scepter of righteousness is the scepter of thy kingdom.”
5 “God is thy throne (or, Thy throne is God) for ever and ever, and the scepter of righteousness is the scepter of his [i.e. God’s] kingdom.”
6 “‘Thy throne, O God, is for ever and ever,’ and ‘the scepter of righteousness is the scepter of his kingdom.’”
Heb 1:8 is one of the texts where NA28/UBS5, TR, Byzantine text and the Orthodox text all agree. Here, it is the W&H text that is the "odd man out".
The NA28 text is:
πρὸς δὲ τὸν υἱόν Ὁ θρόνος σου ὁ θεὸς εἰς τὸν αἰῶνα τοῦ αἰῶνος, καὶ ἡ ῥάβδος τῆς εὐθύτητος ῥάβδος τῆς βασιλείας σου.
I would literally translate this as:
about/unto the Son: "The throne of You, O God, is forever and ever, and the rod/scepter of uprightness [is the] scepter of the kingdom of You."
It is the NASB which follows the W&H text that has "kingdom of Him". However, I and most other versions prefer the NA28/UBS5 text which removes this ambiguity. See UBS5 for details.
Lastly, the NA28/UBS5/TR/Byzantine text of Heb 1:8 agree with that from which it quotes in Ps 45:6 -
Your throne, O God, endures forever and ever, and justice is the scepter of Your kingdom. (same as LXX!!)
As invited by the OP . . . . . .
The fault evidently lies with the Westcott and Hort text, which is unsurprising when one considers the many affiliations of Dr Hort and the colleague of both Westcott and Hort, Dr G Vance Smith, concerning whom the general public were in disagreement - that he should have been on the Revision Commitee of 1881 at all ; but Messrs Westcott and Hort insisted he should be, or they, themselves, would not be.
An examination is recommended, of Dr Scrivener's comparison text of the Authorised Version (in which he academically resources the various texts used by the AV and presents, belatedly, the Greek text behind the AV ; which AV is, effectively, a further text of the TR in English) Dr Scrivener's text having footnotes which highlight every single addition, deletion and alteration, by the W&H text, compared to the TR.
It amounts to about 9,000 changes in 140,000 words.
For comparison, the four presentations of the TR text (Beza, Stephanus, Elzivir and Scrivener) differ in a few hundred places, none of them doctrinally significant, save for Beza's inclusion of certain words in Matthew's account of the birth of Christ.
Notably, the Sinaiticus and Vaticanus texts differ in over 3,000 places in just the four gospel accounts (see Dean John Burgon 'Revision Revised').
Herman Hoskier in his book 'Codex B and its Allies' (Codex B being Vaticanus) proves extensively that there was a recension in about 400 AD influenced by the Coptic/Egyptian manuscripts which was a supposed 'correction' and which influenced the Vaticanus, the Sinaiticus and some other manuscripts.
Burgon's, and later Hoskier's, position is that this recension must be recognised and must be re-corrected in order to arrive back at the original text of the first century.
This is the reason why W&H, in Hebrews 1:8, have the illogical 'his' kingdom and not the blatantly obvious (and fully supported) 'thy kingdom' which is clearly what the Hebrew, of the Masoretic text, means.
W&H strongly supported (in every possible place) their two favourite texts, supposing that antiquity out-weighed every other consideration.
In fact, as Burgon and Hoskier point out, extreme antiquity is not a recommendation.
Why did these two manuscripts survive ?
Why did they not fall to pieces and have to be re-copied ?
Because they were known to be faulty and were not much used - only kept as reference : and were not further copied. 'Re-discovering' these two documents, was not a 'providential epiphany' at all. It was the proof of ancient corruption.
I have many reference books on my shelves - all in good condition.
The bible I bought myself at the age of twenty one (fifty years ago) is falling to pieces, despite being both leather bound and leather-lined, and I have had to replace it.
This is the thoroughly practical reason why the NASB follows the W&H and comes up with something illogical that contradicts the Hebrew.
The real issues are 'Why the recension in the fifth century ?' and 'Why have Hort and Smith, accompanied by Westcott, desired to revert to that recension ?'.
An examination of Dr Scrivener's comparative text (TR/W&H) very clearly reveals the common theological reason for both.
Who is this "His" in Hebrews 1:8, if the Father is speaking to the Son?
First of all, what case are we talking about when it comes to the Son here? Nominative, or, vocative? The answer may well be in the beholding. Names, or even titles (but not limited to these), that are being addressed directly, are said to be in the vocative case. "The Son" here is being merely referenced and is in the accusative case and is therefore the direct object and not the subject of the sentence. "God", even though the subject of the sentence, is not being addressed directly here, so does not need to be in the vocative case. Also, the definite article "the", precedes "God", in all three instances in the Greek (if we include Verse 9), and in Greek, the definite article does not have a vocative case. So, as God is not being addressed directly and is preceded by the definite article, the Greek utilizes the nominative case, as is permitted.
As is often the case in the NASB, as is the case in many a modern day translation, we suffer from "Trinitarian" bias, in the translating of verse 8. The Greek for..."Thy throne, O God, is forever and ever"...(the translation being an unabashed attempt to conflate Jesus with God), is better represented in English as follows..."God is your throne for ever and ever"...and some translations even lean in this direction.
A better rendition of the whole of Hebrews 1:8, as presented in the NWT (rather than the NASB), I think makes the answer to the OP's question quite clear, and is as follows:-
But with reference to the Son: "God is your throne for ever and ever, and the scepter of your kingdom is the scepter of uprightness."
For comparison, here is the verse as rendered in the NASB, 1995 version, where we see the His substituting for kingdom of him, to take the English meaning of the two actual Greek words in question.
But of the Son He says: "Thy throne, O God, is forever and ever, and the righteous scepter is the scepter of His kingdom."
His, in the NASB, is substituted by your kingdom, in the NWT and in both cases, we are talking objective position in the sentence. The His therefore, in question, has to be in reference to the Son and not to God, Himself.
Conclusion
When all is said and done ... and not withstanding the intricacies, not to mention theocratic disputes, in the translation of the Greek regarding Heb 1:8a ... whether we are talking "of you" or "of him", 3rd or, 2nd person singular, in Heb 1:8b, we have to be talking Jesus, as distinct from God, and with Jesus being "the only begotten" of God, the question of deity is not hindered. Trinity, or no Trinity.
IS he speaking to the son?
The text you quoted says, "OF the son He says..." - he is speaking of or about the son - not directly to. Other translations have 'regarding' or 'about' the son He says.
Jesus, while ascended and exalted still has the same God he had as a fleshly man. If the devil is called the 'god of this world' (2Cor 4:4), we can certainly call Jesus the god of the new age or the new world - but always subordinate to his Father and God - the one true God and Father as Jesus himself made quite clear.
Now this is eternal life: that they know you, the only true God, and Jesus Christ, whom you have sent. John 17:3
Hebrews is a quotation of Ps 45 which referred to God. Often the NT writers will quote OT passages and refer to Jesus while doing so - not to replace the truth that was, but to add to it with a new dimension not previously possible. Jesus as God's exalted son is worthy of all praise and of the seat he sits on next to God - he is the firstborn of many brothers.