And his statement—may Allah’s blessings and peace be upon him—“Every innovation is misguidance” embraces both that which is novel in its very foundation and that which is novel only in its manner.
For example, if someone wanted to remember Allah with particular phrases, in a set order or fixed number, without any authentic Sunnah from the Messenger of Allah, we would object—not to the act of remembrance itself, but to prescribing for it a specific form without evidence.

Someone might say, “What do you make of ʿUmar’s words when he instructed Ubayy ibn Kaʿb and Tamim ad-Dari (may Allah be pleased with them both) to lead the people in Ramadan for the night prayer (Tarawih), gathering them behind one imam after they had been praying in scattered groups? ʿUmar came out one night while the people were following their imam and said, ‘What an excellent innovation this is!’ He praised it and still called it an innovation, whereas the Messenger said, ‘Every innovation is misguidance.’”

We answer: This was not a wholly new innovation; rather, it was a relative one. The Prophet led his Companions in prayer for three—or four—nights in Ramadan, standing in prayer with them, then refrained on the third or fourth night and said, “I feared it might be made obligatory upon you.” Consequently, gathering behind a single imam for the night prayer in Ramadan is a practice established by the Prophet himself; he only abandoned it out of fear that it might be imposed on the community.

Afterward matters remained as they were: two men would pray together, three together, or one alone