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.
[He said], "Joseph, O man of truth, explain to us about seven fat cows eaten by seven [that were] lean, and seven green spikes [of grain] and others [that were] dry - that I may return to the people [i.e., the king and his court]; perhaps they will know [about you]."