Matthew 12:39

Adulterous] True religion was represented by the prophets as marriage with Jehovah, so that apostasy from Him was called adultery or fornication (Isaiah 57:3, etc.).

The sign of the prophet Jonas] RV 'Jonah.' 'The sign of the prophet Jonah,' which is mentioned here and in Matthew 16:4 as the only sign to be vouchsafed to unbelievers, is understood by some to be our Lord's Resurrection, and by others His preaching. The question turns upon the authenticity of Matthew 12:40. If this is authentic, the sign is certainly the Resurrection; if it is not authentic, the sign is probably our Lord's preaching, which is expressly compared to Jonah's preaching to the Ninevites (Matthew 12:41; Luke 11:32). The question is a difficult one. Against the authenticity of the v. may be pleaded its omission by St. Luke and the nature of the context, which speaks of the preaching of Solomon and Jonah. In favour of the authenticity may be pleaded the fact that the v. shows clear traces of an Aramaic origin, and therefore presumably formed part of Matthew's Hebrew 'logia'; also that it contains an historic difficulty (the statement that our Lord's body lay for three nights in the grave) which would easily account for its omission by St. Luke. The present writer holds Matthew 12:40, to be an authentic part of the Matthæan 'logia,' and therefore 'the sign of Jonah' to be the Resurrection: cp. Matthew 27:63; John 2:19.