Why should all Chasidim sing to Hashem?
Rashi: From what He did for me, you can trust in Him to benefit you. Even if you are in pain, do not fear!
Radak: This shows that Hashem forgives those who repent to him, lest a Chasid perish via one sin. Even if it was a great sin, but he repents with a full heart, He will accept him.
Radak (6, based on Sotah 11a): Hashem's Midah of benefit is greater than His Midah of punishment.
Malbim: They should sing His praise due to His essence, and thank Zecher Kadsho, i.e. for good things that He did. From His benefits, we remember His deeds and thank His name.
What is the meaning of "v'Hodu l'Zecher Kadsho"?
Radak: This is like 'thank His name.' His name is Zecher Kadsho, for via it we mention Him. We do not know His essence.
