It is narrated from Sayyiduna Jabir (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: Whoever spends a day in the state of Ihram, reciting the Talbiyah until the sun sets, he will have his sins taken away with the setting of the sun, and he will become as pure as the day his mother gave birth to him.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 15008
Hadith Gradingحکم دارالسلام:إسناده ضعيف، عاصم بن عمر ، وعاصم بن عبيد الله ضعيفان، وقد اضطربا فى إسناده