John Gill Commentary Psalms 59:17

"Unto thee, O my strength, will I sing praises: For God is my high tower, the God of my mercy." — Psalms 59:17 (ASV)

Unto thee, O my strength, will I sing
That is, to God, whom he made his strength, and put his trust in for strength, and from whom he received it; and he therefore determined to sing praise to him for it, and give him the glory of it;

for God [is] my defence :
as before in (Psalms 59:9Psalms 59:16) ;

[and] the God of my mercy; (See Gill on Psalms 59:10).