Sayyiduna Abu Hurayrah (may Allah be pleased with him) narrated: the Prophet (peace and blessings be upon him) said: "Whoever relieves a Muslim of some distress, on the Day of Resurrection Allah Almighty will appoint for him two branches of light on the Sirat bridge; by their light a multitude will be illuminated whose number only the Lord of Might can count."
Al-Tabarani recorded it in al-Mu'jam al-Awsat; its chain contains a narrator, al-Ala' bin Salamah bin Uthman, who is da'if (weak).