Who does not say so?
Rashi: The Rasha.
Malbim: Weak birds. Refer to 35:10:2:2.
What is the significance of saying "Aye Eloka Osai?
Rashi: If he would say so, he would fear Him.
Malbim: Weak birds do not say that Hashem does not oversee them, and created them weak. Hashem created them in a way that guards them! Refer to 35:10:2:3. All the more so, Hashem oversees man!
What are "Zemiros ba'Laylah"?
Rashi: This is like "Karmecha Lo Sizmor." He cuts off Resha'im at night, like Amrafel and his colleagues, Egypt and Sancheriv.
Ibn Ezra #1: Hashem causes people to sing at night - "Motza'ei Voker va'Erev Tarnin", "Ki Er'eh Shamecha Ma'ase Etzbe'osecha Yerach v'Kochavim."
Ibn Ezra #2: "Lo" applies also to this - he does not say "Aye Eloka Osai", and he does not sing at night.
Malbim: Hashem put in the nature of birds to sing at night. They fear predators, so they sing to arouse each other to fight for their lives if a predator will come, and to warn each other about fear of night. Via this they are guarded, and the species survives.
