Is the supplication (du'a) mentioned, which Gabriel descended with to the Prophet Muhammad, peace and blessings be upon him, and which begins with "O He who reveals the beautiful and conceals the ugly" and ends with "I ask You, O Allah, not to disfigure my creation with the Fire," along with its accompanying great reward, authentic?

This hadith (definition) was narrated by Al-Hakim and Al-Bayhaqi, but Al-Bayhaqi doubted its authenticity. Al-Dhahabi weakened one of its narrators, Ahmad ibn Muhammad Al-San'ani, just as Ibn Hajar and Bakr Abu Zayd also weakened the hadith and mentioned that it contains the 'an'anah (reporting with "on the authority of") of Ibn Jurayj, who was a mudallis (one who reports in a way that makes it seem he heard directly from his source, but he may not have). The summary of the studies is that the hadith is very weak.