And Allah Most High has made ritual purification obligatory for prayer, as He commanded in the Quran and as is established from the Prophet (may Allah bless him and grant him peace), who said:
“Allah does not accept the prayer of any of you who has invalidated his ablution until he performs ablution again.”
This was recorded in both Sahīh collections. Another authentic report relates that the Prophet (may Allah bless him and grant him peace) said:
“Allah does not accept prayer without purification, nor charity from misappropriated wealth.”
The Muslims have unanimously agreed that ritual purification is obligatory for prayer. What remains to be discussed is what constitutes “prayer.” Those who require ritual purification for a prostration performed on its own have differed among themselves. They have held that it should conclude with the salutation of peace. Some have said that one should pronounce “Allah is Greatest” twice: once to commence it and once for the prostration. Others have said that one should recite the tashahhud (testimony of faith) during it. Yet they have no report from either the Prophet (may Allah bless him and grant him peace) or any of the Companions supporting any of these views. Rather, these are opinions they advanced because they considered it a prayer.
One of them said: “Prayer must consist of at least two units; anything less does not constitute prayer, apart from the single unit of witr.” He cited the report in the Sunan collections from Ibn ʿUmar that the Prophet (may Allah bless him and grant him peace) said:
“Prayer by night and by day is offered two units at a time.”
This was the view of Ibn Hazm. He did not stipulate ritual purification for anything short of that, whether the funeral prayer or anything else. This view, too, is weak, for the hadith is weak. The wording found in the authentic collections and transmitted by reliable narrators is:
“Night prayer is offered two units at a time.”
As for the words “and by day,” this is an addition transmitted only by al-Bāriqī, and it was judged weak by Ahmad