Sayyiduna Abu Musa (may Allah be pleased with him) narrates: the Prophet (peace and blessings be upon him) said: "I prayed for the Arabs, saying: 'O Allah! Whoever among them comes before You in a state of acknowledging You, forgive him for his entire life.' This was also the supplication of Sayyiduna Ibrahim (peace be upon him) and Sayyiduna Isma'il (peace be upon him). On the Day of Resurrection the Banner of Praise (Liwa' al-Hamd) will be in my hand, and on that day the closest of creation to my banner will be the Arabs."
Al-Tabarani recorded it, and al-Bazzar recorded this part of it: "O Allah! Whoever among them comes before You in a state of affirming You and having certainty in You, forgive him." The narrators of both narrations are thiqat (trustworthy).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب المناقب / 16601