Rhyme may depend primarily on sound or terminal letters. Irṣād requires the preceding expression to guide the mind toward the final word. A poet may produce an excellent rhyme that is not sufficiently prepared by the earlier thought to count as irṣād.
If a sentence has developed the themes of inability and limitation, the word tastaṭīʿ (you are able) may become an expected contrast at its close. Verbal pattern can assist, but the principal force comes from semantic preparation.
Not every lucky guess qualifies. The anticipation must arise from the internal structure and recognizable associations of the utterance.