A cubit length — Long enough for his design, and not too long for concealment. His right thigh — Which was most convenient both for the use of his left hand, and for avoiding suspicion.
Related Commentaries of Judges 3:16
Judges 3:16
16 But Ehud made him a dagger which had two edges, of a cubit length; and he did gird it under his raiment upon his right thigh.