Matthew 6:27 - Ellicott's Commentary On The Whole Bible

One cubit unto his stature. — The Greek for the last word admits either this meaning (as in Luke 19:3, and perhaps Luke 2:52) or that of age (as in John 9:21; John 9:23, and Hebrews 11:24). Either gives an adequate sense to the passage. No anxiety will alter our bodily height, and the other conditions of our life are as fixed by God’s laws as that is, as little therefore dependent upon our volition; neither will that anxiety add to the length of life which God has appointed for us. Of the two meanings, however, the last best satisfies the teaching of the context. Men are not anxious about adding to their stature. They are often anxious about prolonging their life. Admit the thought that our days are but “as a span long” (Psalms 39:5), and then the addition of a cubit becomes a natural metaphor. It is to be noted that in the parallel passage in St. Luke (Luke 12:26) this appears as “that which is least,” and which yet lies beyond our power.