A mu’jiza is something which proves the truthfulness of a person who said he was a Prophet. There were conditions for a mu’jiza:
1- Allâhu ta’âlâ made it in the absence of ordinary means, whereby to help His Prophet be confirmed.
2- It had to be extraordinary. Ordinary things, such as the sun’s rising in the East every day or flowers blooming in the spring, could not be mu’jizas.
3- Others had to be incapable of doing it.
4- It had to happen whenever the person who announced his prophethood wished it to.
5- It had to agree with his wish. For example, if he said that he would enliven a certain dead person and if some other marvel took place, for example, if a mountain was broken into two, instead, it would not be a mu’jiza.
6- The mu’jiza happening upon his wish should not belie him. For example, while he was miraculously talking with a certain beast, if the beast said, “This man is a liar,” it would not be a mu’jiza.
7- The mu’jiza should not happen before he said he was a Prophet. Wonders that happened before [the announcement of his prophethood], such as ‘Îsâ’s (‘alaihi ‘s-salâm) talking when he was in a cradle, his having received dates when he asked for dates from a withered-up tree, and in Muhammad’s (‘alaihi ‘s-salâm) childhood, the cleavage of his chest and his heart being cleansed by washing, there being a cloud over his head continuously and his being greeted by trees and stones were not mu’jizas, but karâmas. They are called irhâsât (preparatory signs of a Prophet). They emphasized prophethood. It is possible for such karâmas to happen through Awliyâ as well. Before Prophets were informed of their prophethood, their status was not lower than that of the Awliyâ’. Karâmas were seen from them. A mu’jiza could happen immediately after a Prophet was informed of his prophethood. For example, if he had said that such and such an event would take place a month later, the event would become a mu’jiza when it took place. But it would not be necessary to believe in his prophethood before it took place.