Penitence.

Herman Witsius has written:

“Because in this imperfect state of our sanctification, it cannot altogether be avoided, but at times the godly may fall, and turn a little either to the right hand, or to the left: they are in that case, presently to rise from their fall, and return to their God, unless they would greatly impair their familiarity with him. When he calls us, “return, ye backsliding children, and I will heal your backslidings;” we are directly to answer, “behold we come unto thee, for thou art the Lord our God,” Jer. iii. 12. “yea surely, God will not do wickedly:” In whatever befalls thee, give him thanks; and denying all thy own desires, give up thy will to be swallowed up in his. “Be careful for nothing—and the peace of God, which passeth all understanding, shall keep your hearts and minds through Christ Jesus,” Phil. iv. 6, 7.”

(Witsius, Herman. The Economy of the Covenants Between God and Man, Volume I, Kingsburg, CA: den Dulk Christian Foundation, 1990, p. 437)