When is the supplication recited: "O Allah, I seek refuge in You from associating partners with You knowingly, and I seek Your forgiveness for that which I do not know"?

This supplication is recited when fearing hypocrisy (riya') or polytheism (shirk). On the authority of Abu Musa Al-Ash'ari, may Allah be pleased with him, the Messenger of Allah, peace and blessings be upon him, said: "O people, beware of this shirk, for it is more subtle than the creeping of an ant." When asked how to guard against it, he said: "Say: 'O Allah, we seek refuge in You from associating anything with You knowingly, and we seek Your forgiveness for what we do not know.'" Al-Albani authenticated another narration from Ma'qil ibn Yasar, may Allah be pleased with him, with the wording: "O Allah, I seek refuge in You from associating anything with You while I know, and I seek Your forgiveness for what I do not know." Therefore, one should frequently recite this supplication to be safe from hypocrisy (riya').