Commentaries:
What about the sign of Jonah? Was the prophet in the great fish's belly for a complete 72 hours? The marginal note in Bullinger's Companion Bible for Jonah 1:17 reads: "Three days and three nights. The Hebrew idiom 'three days' can be used for parts of three days (and even of years): but not when the word 'nights' is added" (our emphasis). By the addition of "nights," the expression becomes more specific, precluding the idea of "parts" of days!
Richard T. Ritenbaugh
'After Three Days'
Other Forerunner Commentary entries containing Jonah 1:17:
Isaiah 30:9-11
Jonah 1:17
Matthew 12:38-40
Matthew 16:4
Luke 11:29-30