المعنى الاصطلاحي :

An extraordinary event that Allah causes to happen at the hands of a Prophet before his prophetic mission starts.

الشرح المختصر :

"Irhās" (precursor) is an extraordinary matter that Allah, the Exalted, reveals at the hands of a prophet before he starts his mission, and it serves as a precursor of his prophethood. Examples of this are the extraordinary incidents that occurred at the birth of Prophet Muhammad, may Allah’s peace and blessings be upon him, the blessings and increase in sustenance witnessed by his wet nurse Haleemah As-Sa‘diyyah, the splitting of his chest, and the incidents that occurred while he was traveling in the Levant, besides many others. These are called "irhāsāt" (precursors), whereas the incidents that took place after his mission started are called "āyāt" and "mu‘jizāt" (miracles).

التعريف اللغوي المختصر :

"Irhās": confirmation, establishment. Derived from "rahs", which means laying the foundation for a building. "Irhās-un-nubuwwah": precursor of prophethood; a sign that preceded the mission of the Prophet, called thus because it laid the foundation for prophethood and was a precursor of his upcoming mission.