Sayyidah Maymunah bint Sa'd (may Allah be pleased with her) narrates that she said: O Messenger of Allah! Give us the ruling about the Friday prayer. The Prophet (peace and blessings be upon him) said: In it (that is, the day of Friday) there is an hour in which, whatever supplication a servant makes to his Lord, the Lord answers that supplication. I said: O Messenger of Allah! Which hour is it? He said: That hour is when the imam stands.
Al-Tabarani recorded it in al-Mu'jam al-Kabir, and its chain contains majhul (unknown) narrators.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 3015