What is the measure of moderation in worship, and how can a Muslim know that he is not among those who are extremist or negligent in worship?

The Messenger of Allah, peace and blessings be upon him, is the standard for guiding His servants. Whatever conforms to his guidance is praiseworthy, and whatever deviates from it is blameworthy. The Prophet, peace and blessings be upon him, warned against extremism in religion and exceeding the bounds, as in the narration of the three individuals who wished to increase their worship, and the narration of Uthman ibn Maz'un who used to pray all night and fast all day, both of whom were prohibited from doing so. This is because the Prophet, peace and blessings be upon him, was the most fearful of Allah and the most pious among people, yet he would fast and break his fast, pray and sleep, and marry women. Therefore, whoever seeks something contrary to the Prophet's guidance or adds to it has indulged in extremism and exceeded the bounds of moderation. As for whoever abandons his guidance and is excessive with himself under the pretext of ease, he has erred. The measure for knowing true moderation is to follow what the Prophet, peace and blessings be upon him, was upon, in fulfillment of Allah's saying: "And if you obey him, you will be guided."