This question – along with the good answer of Abu Munir Ibn Ibrahim – permits me to emphasize a couple of concepts that I have often mentioned before… with a Bible fundamentalists turning their noses up at it.
First General Concept
Though I also am a hard believer in the concept of the divine inspiration of the Bible (OT+NT), I do not agree with the claim that every word in the Bible was (necessarily) dictate by God (not to mention the ‘cabalists’, or alike, who claim that every letters of the TaNaKh was fixed by God, to stress a kind of hidden message beneath the TaNaKh text’s surface).
What I see in the Bible is that the Creator did leave each human writer of the Bible to express divine concepts, inside the peculiar style of every of them (according their background, instruction, lifetime period, social environment, vernacular language, et cetera).
Second General Concept
Though I acknowledge the Masoretes’ huge and commendable work to freeze the TaNaKh text so that it could remain stable (through the use of a planned diacritic system), blocking the advance of the degradation of the text, we have to know that the text(s) that the Masoretes worked on were yet degraded (to a certain extent). So, I am not a slavish follower of the Masoretic diacritic system, at all. We have to take note of it, but this ‘system’ also have to pass through a constructive criticism.
Before some of you pronounce an anathema against me, I explain the matter.
Since I believe that the Bible divine inspiration pass through concepts (not single words, necessarily) I am not surprised (whereas Bible fundamentalists have - in this event - the fidgets…) to find in it some linguistic variations in a number of parallel texts.
See for yourselves the following sample Bible parallel texts:
Psa 18 = 2 Sam 22;
Psa 14 = Psa 53;
Jer 52 = 2 Kin 24:18-25:30;
Isa 36:1-38:8 = 2 Kin 18:13-20:11.
Moreover, on the basis of the principle exposed in Job 12:11, “The ear scrutinizes [בחן] speech just as the palate tastes food” (ISV); or, “Does not the ear test [בחן] words and the palate taste food for itself?” (LEB, TLV), we believers are authorized to test the Bible expressions/declarations.
In modern times, we are able to do so through the context, along with all provided textual criticism methodologies, to ascertain what was the original concepts expressed in a given Bible text.
Various other part of the Bible make light on the God’s behaviour toward humans.
From the Bible pages we understand that the Creator is an individual with feelings. The following Bible’s passages are only some examples of this concept: Exo 3:7; Deu 9:7; Jdg 10:16; Psa 106:44; Zec 2:8; Jam 5:11.
So, what about Isa 63:9?
The Hebrew text (with no points) – the so-called Khetib (how-we-find-written) - is:
בכל־צרתם לא צר ומלאך פניו הושׁיעם באהבתו ובחמלתו הוא גאלם וינטלם וינשׂאם כל־ימי עולם
The pivotal expression of the entire concept is לא צר (in this case, “no affliction”).
The wording of Qeri (how-we-have-to-read) said - instead - צר לו, namely, “affliction to him”.
Jamieson-Fausset-Brown's Commentary synthesizes the matter: “he was afflicted — English Version reads the Hebrew as the Keri (Margin), does, ‘There was affliction to Him.’ But the Chetib (text) reads, ‘There was no affliction’ (the change in Hebrew being only of one letter).”
So, the difference between the Qeri and the Khetib made spring two different ideas:
God was afflicted about Israelites (because he felt their feelings in Himself)
According Luther, Vitringa, Clericus, Hitzig, Ewald, Umbreit, Hendewerk, and Knobel.
God was not afflicted about Israelites (because he had the ready solution)
According Montanus, and the Tigurine version.
FOLLOWING THE LXX
It sprang up from the LXX wording.
Probably, starting from a different Hebrew text (different from the texts used by the Masoretes) the LXX’s translators had before their eyes two Hebrew terms to translate: לא, ‘not’ (like the Hebrew Text), and ציר, ‘an envoy’ (a term different from the Hebrew Text’s צר, ‘affliction’).
Again, let us Adam Clarke explains us - with his own words - a slightly variant of this idea:
“I have followed the translation of the Septuagint in the latter part of the eighth, and the former part of the ninth verse; which agrees with the present text, a little differently divided as to thee members of the sentence. They read […]צר tsar [and] they understand as ציר tsir. Και εγενετο αυτοις εις σωτηριαν εκ πασης θλιψεως αυτων· ου πρεσβυς, ουδε αγγελος·, ‘And he was salvation to them in all their tribulation; neither an ambassador nor an angel, but himself saved them.’ An angel of his presence means an angel of superior order, in immediate attendance upon God. So the angel of the Lord says to Zacharias, ‘I am Gabriel, that stand in the presence of God’, Luk 1:19. The presence of Jehovah, Exo 33:14-15, and the angel, Exo 33:20-21, is Jehovah himself; here an angel of his presence is opposed to Jehovah himself, as an angel is in the following passages of the same book of Exodus. After their idolatrous worshipping of the golden calf, ‘when God had said to Moses, I will send an angel before thee - I will not go up in the midst of thee - the people mourned’, Exo 33:2-4. God afterwards comforts Moses, by saying, ‘My presence (that is I myself in person, and not by an angel) will go with thee’, Exo33:14. Αυτος προπορευσομαι σου, ‘I myself will go before thee’, as the Septuagint render it.” (Commentary)
“In all their troubles it was no messenger or angel but his presence that saved them”, New Jerusalem Bible.
“In all their distress it was not an agent “or a messenger, “But His presence saved them”, Concordant Version.
ANOTHER HYPOTHESIS NOT TO UNDERESTIMATE
It revolves around the hypothesis of a scribal substitution.
“The Masora actually does reckon this as one of the fifteen passages in which לוֹ is to be read for לא. (Note: There are fifteen passages in which the keri substitutes לוֹ for לא. See Masora magna on Lev 11:21 (Psalter, ii. 60). If we add Isa 49:5; 1Ch 11:20; 1Sa 2:16, there are eighteen (Comm. on Job, at Job 13:15). But the first two of these are not reckoned, because they are doubtful; and in the third, instead of לּוֹ being substituted for לא, לֹא is substituted for לוֹ (Ges[enius]. Thes. 735, b). 2Sa 19:7 also is not a case in point, for there the keri is לוּ for לא). Jerome was also acquainted with this explanation. He says: ‘Where we have rendered it, ‘In all their affliction He was not afflicted’, which is expressed in Hebrew by lo, the adverb of negation, we might read ipse; so that the sense would be, ‘In all their affliction He, i.e., God, was afflicted’.‘ If we take the sentence in this way, ‘In all oppression there was oppression to Him’, it yields a forcible thought in perfect accordance with the Scripture (compare e.g., Jdg 10:16), an expression in harmony with the usage of the language (compare tsar-lı̄, 2Sa1:26), and a construction suited to the contents (לוֹ = ipsi). There is nothing to surprise us in the fact that God should be said to feel the sufferings of His people as His own sufferings; for the question whether God can feel pain is answered by the Scriptures in the affirmative. He can as surely as everything originates in Him, with the exception of sin, which is a free act and only originates in Him so far as the possibility is concerned, but not in its actuality. Just as a man can feel pain, and yet in his personality keep himself superior to it, so God feels pain without His own happiness being thereby destroyed. And so did He suffer with His people; their affliction was reflected in His own life in Himself, and shared Him inwardly. But because He, the all-knowing, all-feeling One, is also the almighty will, He sent the angel of His face, and brought them salvation.” (Keil & Delitzsch’s Commentary [on Isa 63:9])
Each of these presented hypothesis can be (in the present time) justified according the Bible context (micro- and macro-context). Probably, we have to wait to discover a more ancient Hebrew text that would permit us to resolve the dilemma.
Personally, if I had to be forced to translate in one of this way, I – in the present time - maybe should prefer to opt for the ‘LXX hypothesis’.
Anyway – interestingly - any hypothesis we choose, all of them prove to be in keeping with God’s personality (as it is presented in the Bible’s pages, along with the creation witnessing [Rom 1:20]).