John 6:5

"And as He lifted up His eyes, He beheld a great company." This showeth that He sat not at any time idly with the disciples, but perhaps carefully conversing with them, and making them attend and turn towards Him, a thing which peculiarly marks His tender care, and the humility and condescension of His demeanor towards them. For they sat with Him, perhaps looking at one another; then having lifted up His eyes, He beheld the multitudes coming unto Him.

Wherefore then doth He ask "Philip"? He knew which of His disciples needed most instruction; for this is he who afterwards said, "Show us the Father, and it sufficeth us", and on this account Jesus was beforehand bringing him into a proper state. For had the miracle simply been done, without any introduction, the marvel would not have seemed so great, but now He beforehand constraineth him to confess the existing want, that knowing the state of matters he might be the more exactly acquainted with the magnitude of the miracle about to take place.

(de Con. Evang. l. ii. c. xlvi) But if our Lord, according to John's account, on seeing the multitude, asked Philip, tempting him, whence they could buy food for them, it is difficult at first to see how it can be true, according to the other account, that the disciples first told our Lord, to send away the multitude; and that our Lord replied, They need not depart; give ye them to eat. (Matt. 25:16) We must understand then it was after saying this, that our Lord saw the multitude, and said to Philip what John had related, which has been omitted by the rest.

If we compare the accounts of the different Evangelists, we shall find very clearly, that there was an interval of a year between the beheading of John, and our Lord's Passion. For, since Matthew says that our Lord, on hearing of the death of John, withdrew into a desert place, where He fed the multitude; and John says that the Passover was nigh, when He fed the multitude; it is evident that John was beheaded shortly before the Passover. And at the same feast, the next year Christ suffered. It follows, When Jesus then lifted up His eyes, and saw a great company come unto Him, He saith unto Philip, Whence shall we buy bread, that these may eat? When Jesus lifted up His eyes, this is to show us, that Jesus was not generally with His eyes lifted up, looking about Him, but sitting calm and attentive, surrounded by His disciples.

He asks him this question, not for His own information, but in order to show His yet unformed disciple his dulness of mind, which he could not perceive of himself.