Jeremiah 9:13
And the LORD saith, Because they have forsaken my law which I set before them, and have not obeyed my voice, neither walked therein; And the LORD saith, Because they have forsaken my law which I set before them, and have not obeyed my voice, neither walked therein;
The Lord gives as His stated reason for judgment that the people had forsaken His law which He had set before them, had not obeyed His voice, and had not walked in it. That forsaking meant a refusal to obey His voice and to live by His instruction rather than walking in His ways. This rejection of His law was part of why the land became desolate, with the surrounding context joining to it their following of their own hearts and Baalim and His resulting punishment upon them.
The same word applies to those who forsake God's law and choose their own way, disregarding the principles He has laid down and acting from their own desires instead of relying on divine wisdom and power. In that application it speaks particularly to men in positions of trust who ignore God's principles, take this self-chosen course, and indulge selfishness instead of looking to Him. In this self-chosen course selfishness and ambition reveal the failure to obey God. That condition calls for repentance and confession.