John 10:4
When he has brought out all his own, he goes before them, and the sheep follow him, for they know his voice.If we spend time with the Master, live in the Word, and pray in faith, we will know his voice. When he speaks to us, we will hear him. Pray that we do hear God.
from "30 Ways to Pray for Missionaries," compiled by Elaine Helms for the NAMB. (the full list in pdf form is available here)