What is the ruling on saying "الزاكيات لله" (All purifications are for Allah) in the Tashahhud? Is it considered an innovation (bid'ah), especially since our master Umar (may Allah be pleased with him) said it on the pulpit and the Companions did not object to him, while some sources mention that it is specific to the Maliki school of thought, and Sheikh Ibn Baz issued a fatwa against saying it?

Adding "al-zakiyat lillah" (all good pure things are for Allah) in the Tashahhud is not an innovation (bid'ah). Rather, it was reported in the Tashahhud of 'Umar ibn al-Khattab, may Allah be pleased with him, and Sheikh al-Albani authenticated this narration. Imam Malik chose this Tashahhud because 'Umar, may Allah be pleased with him, taught it to the people from the minbar in the presence of the Companions, and no one repudiated it, which indicates their affirmation and agreement with it. This addition was also reported in the Tashahhud of 'Aishah, may Allah be pleased with her.