Fa-nʿaynī asks for the announcement of someone's death, accompanied by acknowledgment of his qualities. Shuqqī al-jayb refers to tearing the neckline or opening of a garment in mourning; al-jayb here is not a modern money pocket.
The literary point is the speaker's desire to be remembered in proportion to his worth. The line documents a historical form of mourning and an aspiration to reputation; describing that practice is not the same as determining its religious permissibility.