Musannaf Ibn Abi Shaybah

Hazrat Saeed (may Allah be pleased with him) and Hazrat Hasan (may Allah be pleased with him) state that Hazrat Umar (may Allah be pleased with him) gave an impotent man a respite of one year; if he gained the ability to have intercourse, then fine, otherwise separation would be effected between the husband and wife, and the woman would be required to observe the waiting period (iddah).

Hazrat Ata (may Allah have mercy on him) says that when a year of respite passes, the woman will observe the waiting period ('iddah) of a divorced woman, even if the impotent man has not given divorce.

Hazrat Hasan (may Allah be pleased with him) says that when separation is made between an impotent man and his wife, then 'iddah (waiting period) will be obligatory upon her.

Hazrat Urwah (may Allah have mercy on him) says that when separation is made between an impotent man and his wife, then 'iddah (waiting period) will be obligatory upon her.