Musannaf Ibn Abi Shayba 21:136

Yazid ibn Harun narrated to us, [who said] Mas'ar informed us, from Muhammad ibn Abd al-Rahman, from Taysalah, from Ibn Umar, who said: Whoever says, after every prayer and when he takes to his bed: "Allah is the Greatest, the Great, the number of the even and the odd, and the perfect, good, and blessed words of Allah" (three times), and "There is no god but Allah" (the same amount), it will be for him a light in his grave, a light upon the bridge, and a light upon the path, until it enters him into Paradise, or he enters Paradise.