Luke 9:51

And it came to pass, when the time was come
Or "days were fulfilled", an usual Hebraism; when the period of time fixed for his being in Galilee was come to an end: when he had fulfilled his ministry, and finished all his sayings, and wrought all the miracles he was to work in those parts; when he was to quit this country, and go into Judea, and up to Jerusalem, signified in the next clause:

that he should be received up;
or as all the Oriental versions rightly render the words, "when the time, or days of his ascension were fulfilled"; not of his ascension to heaven, as interpreters generally understand the passage, because the word is used of that, in ( Mark 16:19 ) ( Acts 1:2 Acts 1:11 Acts 1:22 ) ( 1 Timothy 3:16 ) much less as others, of his being taken and lifted up from the earth upon the cross, and so signifies his crucifixion, and sufferings, and death; for of neither of these can it be said, that the time of them was come, or the days fulfilled, in which either of these should be: for if Christ was now going to the feast of tabernacles, as some think, it must be above half a year before his death, and still longer before his ascension to heaven: and if to the feast of dedication, it was above three months to his ascension: hence interpreters that go this way, are obliged to interpret it, that the time drew near, or was drawing on, or the days were almost fulfilled; whereas the expression is full and strong, that the time was come, and the days were fulfilled; and which was true in the sense hinted at, that now the time was up, that Jesus must leave the low lands of Galilee, having finished his work there; and go into the higher country of Judea, and so up to Jerusalem; for of his ascension from Galilee to Jerusalem are the words to be understood; (See Gill on Matthew 19:1)

(See Gill on Mark 10:1) And it is observable that after this, he never went into Galilee any more; and this sense is confirmed by what follows:

he steadfastly set his face to go to Jerusalem;
or "strengthened his face", as the Vulgate Latin and Ethiopic versions; set his face like a flint, as in ( Isaiah 1:7 ) denoting not impudence, as hardening of the face is used in ( Proverbs 21:29 ) but boldness, courage, constancy and firmness of mind: or "he prepared his face", as the Syriac; or "turned his face", as the Arabic, he looked that way, and set forward; or as the Persic version renders it, "he made a firm purpose", he resolved upon it, and was determined to go to Jerusalem, his time being up in Galilee; and though he knew what he was to meet with and endure; that he should bear the sins of his people, the curse of the law, and wrath of God; that he should have many enemies, men and devils to grapple with, and undergo a painful, shameful, and accursed death; yet none of these things moved him, he was resolutely bent on going thither, and accordingly prepared for his journey; (See Gill on 2 Kings 12:17).