Psalms 44:21

Shall not God search this out?
&c.] Undoubtedly he would, was it so, and expose it, and punish for it; as he will the Balaamites and children of Jezebel, ( Revelation 2:18-23 ) ; this seems to be an appeal to God for the truth of all that the church had said concerning her steadfastness and integrity under the most trying exercises;

for he knoweth the secrets of the heart;
whether the heart is turned back, or there is any inclination to apostatize from God, or his name is forgotten in it; as well as whether in fact the hand has been stretched out, or prayer made to a strange god, ( Jeremiah 17:9 Jeremiah 17:10 ) .