It is narrated from Sayyiduna Jabir (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever recites 'Say: He is Allah, the One' fifty times every day will be called out to from his grave on the Day of Resurrection: 'Rise and enter Paradise.'"
Hadith Referenceالمعجم الأوسط / باب الياء / 9446
Hadith Takhrij«أخرجه الطبراني فى «الصغير» برقم: 1134»