Abd al-Rahman bin Abi Layla (may Allah have mercy on him) narrates from his father (may Allah be pleased with him): The Messenger of Allah (peace and blessings be upon him) was performing a voluntary prayer, and I heard him (peace and blessings be upon him) saying: "'Allahumma inni a'udhu bika min al-nar, waylun li-ahl al-nar' (O Allah, I seek refuge in You from the punishment of the Fire. Woe and ruin to the people of the Fire)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3690