Who said: "May my mother, my maternal and paternal aunts, my fathers, my soul, and my wealth be sacrificed for the Messenger of Allah," and what was the occasion for it?

This phrase appeared in an elegy recited by Safiyyah bint Abd al-Muttalib (may Allah be pleased with her) for the Messenger of Allah (peace and blessings be upon him) after his passing. It was mentioned by Al-Tabarani in Al-Mu'jam al-Kabir.