Wherefore I put thee in remembrance that thou stir up the gift of God, which is in thee by the putting on of my hands. Stir up the gift of God, which is in thee - The gift which Timothy had received was the Holy Spirit; and through him, a particular power to preach and defend the truth. This gift is represented here, under the notion of a fire, which, if it be not frequently stirred up, and fresh fuel added to it, will go out. This is the precise idea which the apostle had in his mind; hence the term αναζωπυρειν, which signifies to stir up the fire; to add fresh fuel to it. From this it plainly appears, that if Timothy had not continued to be a daily worker with God, he would have received the grace of God in vain. The Latins have a similar metaphor, excitare igniculos ingenii, to stir up the sparks of genius.
By the putting on of my hands - See on 1 Timothy 4:14 (note).