“Therefore Eli said unto Samuel, Go, lie down: and it shall be, if he call thee, that thou shalt say, Speak, LORD; for thy servant heareth. So Samuel went and lay down in his place. ¹⁰And the LORD came, and stood, and called as at other times, Samuel, Samuel. Then Samuel answered, Speak; for thy servant heareth.” I Samuel 3:9-10

Even an old backslidden priest can teach someone how to serve God. Eli instructed Samuel that when he hears his name called again say, “Speak, Lord; for thy servant hears.” That is some good teaching.