Being forty days tempted - That is, through forty days he was "tried" in various ways by the devil. The temptations, however, which are recorded by Matthew and Luke did not take place until the forty days were finished. See Matthew 4:2-3.
He did eat nothing - He was sustained by the power of God during this season of extraordinary fasting.

Being forty days tempted of the devil,.... The Vulgate Latin, Syriac, Persic, and Ethiopic versions read the phrase, "forty days", in connection with the latter part of the preceding verse; according to which the sense is, that Jesus was led by the Spirit forty days in the wilderness, before he was tempted by Satan, and in order to it: but our reading is confirmed by Mark 1:13 who affirms, as here, that he was so long tempted by Satan; as he might be invisibly, and, by internal suggestions, before he appeared visibly, and attacked him openly, with the following temptations. The Ethiopic version adds, "and forty nights": and such were these days in which Christ was in the wilderness, and fasted, and was tempted there: they, were such as included nights, as well as days; see Matthew 4:2
and in those days he did eat nothing not any sort of food whatever; he tasted of no kind of eatables or drinkables, during the whole space of forty days; nor in the nights neither, in which the Jews allowed persons to eat in times of fasting; See Gill on Matthew 4:2. And this entire abstinence, as it shows the power of Christ in the supporting of his human nature, without food, for such a time, and the disadvantages under which, as man, combated with Satan; so, that this fast was never designed as an example to his followers, and to be imitated by them:
and when they were ended; the forty days, and forty nights:
he afterward hungered; which he did not before; and which shows the truth of his human nature; and is mentioned to observe the occasion of the following temptation, and the advantage on the tempter's side.