John Lightfoot on Matthew 12:40

[The Son of man shall be three days and three nights in the heart of the earth.] 1. The Jewish writers extend that memorable station of the unmoving sun at Joshua's prayer to six-and-thirty hours; for so Kimchi upon that place: "According to more exact interpretation, the sun and moon stood still for six-and-thirty hours: for when the fight was on the eve of the sabbath, Joshua feared lest the Israelites might break the sabbath: therefore he spread abroad his hands, that the sun might stand still on the sixth day, according to the measure of the day of the sabbath, and the moon, according to the measure of the night of the sabbath, and of the going-out of the sabbath; which amounts to six-and-thirty hours."

II. If you number the hours that passed from our Saviour's giving up the ghost upon the cross to his resurrection, you shall find almost the same number of hours; and yet that space is called by him "three days and three nights," when as two nights only came between, and only one complete day. Nevertheless, while he speaks these words, he is not without the consent both of the Jewish schools, and their computation. Weigh well that which is disputed in the tract Schabbath, concerning the uncleanness of a woman for three days; where many things are discussed by the Gemarists concerning the computation of this space of three days. Among other things these words occur; "R. Ismael saith, Sometimes it contains four Onoth sometimes five, sometimes six. But how much is the space of an Onah? R. Jochanan saith either a day or a night." And so also the Jerusalem Talmud; "R. Akiba fixed a day for an Onah, and a night for an Onah: but the tradition is, that R. Eliezar Ben Azariah said, A day and a night make an Onah, and a part of an Onah is as the whole." And a little after, R. Ismael computeth a part of the Onah for the whole.

It is not easy to translate the word Onah into good Latin: for to some it is the same with the half of a natural day; to some it is all one with a whole natural day. According to the first sense we may observe, from the words of R. Ismael, that sometimes four Onoth, or halves of a natural day, may be accounted for three days: and that they also are so numbered that one part or the other of those halves may be accounted for a whole. Compare the latter sense with the words of our Saviour, which are now before us: "A day and a night (saith the tradition) make an Onah, and a part of an Onah is as the whole." Therefore Christ may truly be said to have been in his grave three Onoth, or three natural days (when yet the greatest part of the first day was wanting, and the night altogether, and the greatest part by far of the third day also), the consent of the schools and dialect of the nation agreeing thereunto. For, "the least part of the Onah concluded the whole." So that according to this idiom, that diminutive part of the third day upon which Christ arose may be computed for the whole day, and the night following it.