المُعجِزَةُ عَلامةٌ للَّهِ‏ لا يُعطيها إلّا أنبِياءَهُ ورُسُلَهُ وحُجَجَهُ؛ لِيُعرَفَ بهِ صِدقُ الصّادِقِ مِن كِذبِ الكاذِبِ.

The miracle is a sign pointing to Allah which none can produce but His prophets, His messengers and His proofs, in order that the truth of the truthful one be distinguished from the lie of the liar.

Ilal al-Shara’i , p. 122, no. 1