This generation - Ἡ γενεα αὑτη, This very race of men. It is certain that this word has two meanings in the Scriptures; that given in the text, and that above. Generation signifies a period of a certain number of years, sometimes more, sometimes less. In Deuteronomy 1:35; Deuteronomy 2:14, Moses uses the word to point out a term of thirty-eight years, which was precisely the number in the present case; for Jerusalem was destroyed about thirty-eight years after our Lord delivered this prediction. But as there are other events in this chapter, which certainly look beyond the destruction of Jerusalem, and which were to take place before the Jews should cease to be a distinct people, I should therefore prefer the translation given above. See on Matthew 24:34 (note).

that.

Matthew 16:28 Truly I say to you, There be some standing here, which shall not taste of death, till they see the Son of man coming in his kingdom.

Matthew 23:36 Truly I say to you, All these things shall come on this generation.

Matthew 24:34 Truly I say to you, This generation shall not pass, till all these things be fulfilled.

Luke 21:32 Truly I say to you, This generation shall not pass away, till all be fulfilled.

"But the End of all Things is at Hand, be Ye Therefore Sober and Watch unto Prayer. "
1 Pet. iv. 7.--"But the end of all things is at hand, be ye therefore sober and watch unto prayer." If ye would ask what ye should do till Christ come again, or what should be your exercise and employment in this old age of the world, here ye have it in a word, "be sober, and watch unto prayer." When Christ was to go away to his Father, and leave his disciples in this world, as he left them not orphans, or comfortless, without the Comforter, so neither left he them without counsel and direction. …
Hugh Binning—The Works of the Rev. Hugh Binning

Texts Explained; Eleventhly...
Chapter XXVIII.--Texts Explained; Eleventhly, Mark xiii. 32 and Luke ii. 52 Arian explanation of the former text is against the Regula Fidei; and against the context. Our Lord said He was ignorant of the Day, by reason of His human nature. If the Holy Spirit knows the Day, therefore the Son knows; if the Son knows the Father, therefore He knows the Day; if He has all that is the Father's, therefore knowledge of the Day; if in the Father, He knows the Day in the Father; if He created and upholds all …
Athanasius—Select Works and Letters or Athanasius

Content of Revelation. God Three in one and the Incarnation.
To dwell at length on the theology of Athanasius under this head is unnecessary here, not because there is little to say, but partly because what there is to say has been to some extent anticipated above, §§2, 3, and ch. ii. pp. xxxii., xxxvi., partly because the history of his life and work is the best exposition of what he believed and taught. That his theology on these central subjects was profoundly moulded by the Nicene formula is (to the present writer at least) the primary fact (see …
Athanasius—Select Works and Letters or Athanasius