2 Samuel 9:8

And he bowed himself, and said, What is thy servant, that thou shouldest look upon such a dead dog as I am?

Cross-reference

In 2 Samuel 16:9, Abishai uses 'dead dog' to insult Shimei, in contrast to Mephibosheth's humble self-application here.

In 2 Samuel 19:28, Mephibosheth again humbles himself before David, directly echoing his earlier 'dead dog' statement.

In 2 Samuel 3:8, Abner calls himself a 'dog's head', similar to Mephibosheth's 'dead dog' self-deprecation.

In 1 Samuel 24:14, David calls himself a 'dead dog' before Saul, exactly matching Mephibosheth's self-deprecation here.