Rajaʿā is a dual past verb, referring to the pair. In bi-amrihimā, amr carries a dual possessive suffix. Ilā dhī mirrah points to firm judgment or resolve.
The second hemistich, najḥu ṣarīmatin ibrāmuhā, has a nominal-sentence structure: successful resolve consists in making the decision firm. A moment in an animal narrative thus acquires the quality of a general maxim.