‘Are there any biblical examples where “after three days and three nights” may not mean exactly 72 hours? Yes, 1 Samuel 30 is an example. The account in this chapter is about David and the Amalekites, and certain events in the village of Ziklag. Verse one tells us that, “David and his men reached Ziklag on the third day” (emphasis ours throughout). Upon arriving at Ziklag, David encountered an Egyptian, the slave of an Amalekite. He told David, “My master abandoned me when I became ill three days ago” (verse 13). The account also says that the Egyptian had not eaten or drunk for “three days and three nights” (verse 12).
‘”On the third day” is not necessarily three full days. In fact, it would be less than 72 hours. “Three days ago” is equally vague, as it could be less than three full days. Yet, this time is equated with “three days and three nights.” It’s certainly possible, or even probable, that we are not dealing with a full 72-hour period here. If that is the case, then “three days and three nights” could be an idiomatic expression that would refer to parts of three days. 1 Samuel 30 indicates that “three days and three nights” was an expression that did not necessarily mean a full 72 hours. Other examples where variants of the expression “three days” are used includes the following passages: Genesis 42:17-18 (”for three days” = “on the third day”); 2 Chronicles 10:5, 12 (”three days later” = “in three days”) and Esther 4:16-5:1 (”for three days” = “on the third day”).’
http://www.gci.org/jesus/howlong
Thanks for your input and examples. Is there any indication in the Samuel passage that the Egyptian slave really hadn’t eaten for three days and three nights? It seems he could have been telling the truth. But even if he was lying or exaggerating, it would be understandable under the circumstances. I’m less inclined to believe Jesus said ‘three days and three nights’ when what He meant was ‘three days’. I for one have never said ‘three nights’ when I meant ‘two nights’. Something to think about, anyway.