Sayyiduna Ali bin Abi Talib (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "The people of my Ummah will continue to pray these four rak'ahs before Asr until they walk upon the earth in a state where they have definitely been forgiven."
Al-Tabarani recorded it in al-Mu'jam al-Awsat; its chain contains Abd al-Malik bin Harun bin Antarah, who is matruk (abandoned).