As Jesus has in view the Old Testament, which was written mostly in Hebrew, these are references to the Hebrew alphabet. The smallest Hebrew letter was the yodh (י), which in Greek is represented by the similarly smallest letter, the iota. The dot (in some translations, the least stroke of a pen
) is the Hebrew alphabet a little hook that distinguishes one letter from another (for example, it distinguishes a beth (ב) from a kaph (כ)). 1 Jesus is hereby emphasizing that everything that God has revealed will be accomplished. Nothing that was prophesied in any part of Scripture, no matter how small or insignificant it may seem, will be left unfulfilled (see 2 Corinthians 1:18). The implication is that one must not disobey the law or do away with it, but interpret the Law (and the Prophets), and apply it in the light of Jesus’ work of fulfillment. 2
18 For truly, I say to you, until heaven and earth pass away, not an iota, not a dot, will pass from the Law until all is accomplished.