Sayyiduna Abdullah bin Amr bin al-As (may Allah be pleased with him) said: I came while the Prophet (peace and blessings be upon him) was among some of his Companions, among whom was Sayyiduna Umar bin al-Khattab (may Allah be pleased with him). I caught the last part of his (peace and blessings be upon him) talk; the Prophet (peace and blessings be upon him) was saying: "Whoever prays four rak'ahs before Asr, the Fire will not touch him."
Al-Tabarani recorded it in al-Mu'jam al-Awsat; its chain contains Abd al-Karim Abu Umayyah, who is da'if (weak).
In al-Mu'jam al-Kabir it is transmitted in abridged form with these words: "Allah Almighty will make him forbidden to Hellfire."