What is the criterion for the concept of bid‘ah (innovation in religion), and why are some actions of the Companions, for which there was no prior textual evidence, such as a Companion’s saying after rising from rukū‘ (bowing): “Our Lord, and to You be praise, much good and blessed praise,” not considered bid‘ah, whereas introducing another dhikr (remembrance of God) or du‘ā’ (supplication) in our time is considered bid‘ah?

What the Companions did and what the Prophet (peace be upon him) approved was not an innovation (bid'ah), because that era was a time of legislation. Innovation has been defined as what was introduced after the time of the Prophet (peace be upon him), such as the definition given by Muhammad al-Khadimi al-Hanafi: "Innovation in Islamic law is introducing what did not exist during the era of the Messenger of Allah (peace be upon him)."

However, not everything the Companions did was free from innovation. The Prophet (peace be upon him) denounced some of their actions that fell under the category of innovation, such as his disapproval of those who vowed not to seek shade, or not to sit, or not to speak, and his command to them to complete their fast, sit, seek shade, and speak. Similarly, the Prophet (peace be upon him) denounced monasticism to Uthman ibn Maz'un (may Allah be pleased with him). Aisha (may Allah be pleased with her) said that the Prophet (peace be upon him) said to Uthman ibn Maz'un: "O Uthman, monasticism has not been prescribed for us. Do you not have a good example in me?" In another narration: "I was sent with the easy and tolerant Hanifiyyah, and I was not sent with the innovated monasticism." And similarly, his disapproval of those who said: "I will not marry women," or "I will not eat meat," or "I will not sleep on a bed."

So, what the Prophet (peace be upon him) denounced in some Companions falls under the category of innovation. Imam al-Shatibi's definition of innovation is more comprehensive: "A newly invented way in religion that resembles the legal one, intended by its observance to exaggerate in worship to Allah, Glorified be He."