Angels lack free will

 Rambam 13 Principles

The fifth principle That He is the One that is fitting to serve and to exalt and to make His greatness known and to do His commandments; and not to do this to that which is below Him in existence - from the angels and the stars and the spheres and the elements and what which is composed of them. As they are all designed and there is no judgement and no free choice in their actions - only to Him, may He be blessed. And so [too], it is not fitting to serve them in order that they be intermediaries to bring them closer to Him, but rather to Him alone should they direct their thoughts and leave everything besides Him. And this fifth principle is that idolatry (worship of others) is prohibited, and most of the Torah prohibits this.