Irṣād, sometimes called tashīm, occurs when the wording preceding a closing expression prepares the listener to anticipate that close. The merit lies not merely in rhyme, but in the earlier discourse guiding the mind toward a suitable completion.
وهو أن يجعل قبل العجز من الفقرة ما يدل عليه
It is to place before the close of a clause something that indicates that close.
The final rhyme in verse and the conclusion of a prose clause are obvious positions for the effect, but the device itself depends on anticipation created through the preceding wording and sense.