Truthfulness is approached here from several angles: the Quran and the Messenger ﷺ confirm what came before them, and none is truer in speech than Allah. The verses mention prophets of perfect truthfulness, genuine truthfulness made of faith and deeds, the reward of the people of truth, the command to be with the truthful, and Mary, daughter of ʿImran, described as truthful.
Verses gathered from a topical index of the Quran, in Mushaf order; every verse is quoted in full.
The Messiah, son of Mary, was not but a messenger; [other] messengers have passed on before him. And his mother was a supporter of truth. They both used to eat food. Look how We make clear to them the signs; then look how they are deluded.