Sayyiduna Wa'il bin Hujr relates: I saw the Prophet (peace and blessings be upon him) begin the prayer, and when he finished reciting Surah al-Fatihah, he said 'Amin' three times. (Allamah al-Haythami says:) I say:
Ibn Majah recorded it, but he did not record these words: "three times".
Al-Tabarani recorded it in al-Mu'jam al-Kabir, and its narrators are thiqat (trustworthy).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 2667