Or he may have had direct contact with someone who witnessed such things, or been told about them by someone he regards as truthful.
Such things have always happened frequently to people in every age, and they recount them to one another. This is common (1) among many Muslims.
Or he may himself have experienced some of these occurrences.
Consider the armies of Abū Bakr and Umar and their subjects: they experienced extraordinary occurrences greater than that. One example is al-ʿAlāʾ ibn al-Hadramī’s crossing over water, as mentioned earlier; this is greater than the drying up of water. Other examples include his supplication for rain; the cattle that spoke to Saʿd ibn Abī Waqqās at the Battle of al-Qādisiyya; Umar’s call, “O Sāriya, make for the mountain!” while Umar was in Medina and Sāriya was in Nahāwand; and Khālid ibn al-Walīd’s drinking poison.
Another example is Abū Muslim al-Khawlānī’s being thrown into the fire, which became cool and safe for him. It was al-Aswad al-ʿAnsī, the lying claimant to prophethood, who threw him into it. He had seized control of Yemen, and when Abū Muslim refused to believe in him, he threw him into the fire. Allah made it cool and safe for him, and he emerged wiping his forehead. There are other examples whose description would take too long.
It should also be understood that extraordinary occurrences are granted to Allah’s friends according to their need. Someone living among disbelievers, hypocrites, or the defiantly sinful needs them to strengthen his certainty, so they manifest through him as light appears in darkness.
For this reason, some of these occurrences are found more frequently among many who are less virtuous than among those who are more virtuous, because of their need for them.