Rashi: I will engage, like "Yish'eh ha'Adam Al Osehu" (Yeshayah 17:7), "v'Al Yish'u b'Divrei Shaker" (Shemos 5:9).

Radak: I get Simchah [when I contemplate your Chukim]. Malbim - this is even for Chukim. He has Emunah that great secrets are hidden in them. This testifies that his Nefesh is supreme and goes in Kodesh in wondrous ways. Its bond to Hashem obligates doing wonders above man's understanding. Matters without a reason, one is prone to forget them; [Your Chukim] are dear and important to me; I will always remember them.

Radak (1): Amirah and Dibur are a Klal for all Mitzvos; they also refer to Hashem's promises. Dibur refers also to Hashem's desire to create the world.