John Calvin Commentary Luke 22:36

"And he said unto them, But now, he that hath a purse, let him take it, and likewise a wallet; and he that hath none, let him sell his cloak, and buy a sword." — Luke 22:36 (ASV)

But now let him who has a purse take it. In metaphorical language, He threatens that they will soon encounter great troubles and fierce attacks. This is just as when a general, intending to lead soldiers into the battlefield, calls them to arms, ordering them to set aside every other concern and think of nothing but fighting, not even to consider how to obtain food. For He shows them—as is usually done in cases of extreme danger—that everything must be sold, even to the scrip and the purse, to provide them with arms.

Yet He does not call them to an external conflict. Instead, using the comparison of fighting, He warns them of the severe struggles of temptations they must undergo and the fierce attacks they must endure in spiritual contests.

So that they might more willingly entrust themselves to God's providence, He first reminded them, as I have said, that God took care to supply them with what was necessary, even when they carried no supplies of food or clothing with them. Having experienced such abundant and timely provisions from God, they ought not, in the future, to entertain any doubt that He would provide for all their needs.