Sayyiduna Abu Umamah (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings be upon him) said: "Whoever goes out of his house in a state of ablution for an obligatory prayer, his reward is like the reward of a pilgrim performing Hajj in the state of ihram; and whoever goes out for the Duha (forenoon) prayer, with nothing prompting him except that, his reward is like the reward of one performing Umrah. And one prayer after another, with no idle talk between them, is recorded in Illiyyin."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4973