Ray has already given you the right answer. All I can do now is to add a handful of verses to back it up.
Yes, Jesus was talking about His transfiguration. Both Matthew and Mark blink at you while they tell you that it happened on the seventh day. They hyperlink to Genesis 2:1-3 and the never-ending reality of the rest with God. Luke tackles it from a different angle and portrays the event as the new beginning, the eight day. All three gospels have Peter proposing to built three sukkas for Jesus, Moses and Elias which is another rabbit hole. Jesus' appearance on the mountain was the foretaste of the kingdom given to Peter, John and James before their death.
1 And after six days Jesus taketh Peter, James, and John his brother, and bringeth them up into an high mountain apart,
2 And was transfigured before them: and his face did shine as the sun, and his raiment was white as the light.
5 And he brought him forth abroad, and said, Look now toward heaven, and tell the stars, if thou be able to number them: and he said unto him, So shall thy seed be (not only quantitive but also qualitative).
2 And many of them that sleep in the dust of the earth shall awake, some to everlasting life, and some to shame and everlasting contempt.
3 And they that be wise shall shine as the brightness of the firmament; and they that turn many to righteousness as the stars for ever and ever.
43 Then shall the righteous shine forth as the sun in the kingdom of their Father. Who hath ears to hear, let him hear.
39 All flesh is not the same flesh: but there is one kind of flesh of men, another flesh of beasts, another of fishes, and another of birds.
40 There are also celestial bodies, and bodies terrestrial: but the glory of the celestial is one, and the glory of the terrestrial is another.
41 There is one glory of the sun, and another glory of the moon, and another glory of the stars: for one star differeth from another star in glory.
42 So also is the resurrection of the dead. It is sown in corruption; it is raised in incorruption:
43 It is sown in dishonour; it is raised in glory: it is sown in weakness; it is raised in power:
44 It is sown a natural body; it is raised a spiritual body. There is a natural body, and there is a spiritual body.
45 And so it is written, The first man Adam was made a living soul; the last Adam was made a quickening spirit.
46 Howbeit that was not first which is spiritual, but that which is natural; and afterward that which is spiritual.
47 The first man is of the earth, earthy: the second man is the Lord from heaven.
48 As is the earthy, such are they also that are earthy: and as is the heavenly, such are they also that are heavenly.
49 And as we have borne the image of the earthy, we shall also bear the image of the heavenly.
50 Now this I say, brethren, that flesh and blood cannot inherit the kingdom of God; neither doth corruption inherit incorruption.
51 Behold, I shew you a mystery; We shall not all sleep, but we shall all be changed,
52 In a moment, in the twinkling of an eye, at the last trump: for the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed.
53 For this corruptible must put on incorruption, and this mortal must put on immortality.
1 Corinthians 15
23 And the city had no need of the sun, neither of the moon, to shine in it: for the glory of God did lighten it, and the Lamb is the light thereof.
24 And the nations of them which are saved shall walk in the light of it: and the kings of the earth do bring their glory and honour into it.
16 I Jesus have sent mine angel to testify unto you these things in the churches. I am the root and the offspring of David, and the bright and morning star.