I went out with the Prophet ﷺ on a journey, and he passed by a man who was reciting "Say, O you disbelievers" [Kafirun 109:1]. He said, "As for this one, he has freed himself from polytheism."Then he passed another man reciting "Say, He is Allah, the One" [Ikhlas 112:1], and the Prophet ﷺ said, "Through this, Paradise has become guaranteed for him."
قال حدثنا أبو النضر قال حدثنا المسعودي عن مهاجر أبي الحسن
خرجت مع النبي ﷺ في سفر فمر برجل يقرأ قل يا أيها الكافرون قال أما هذا فقد برئ من الشرك قال وإذا آخر يقرأ قل هو الله أحد فقال النبي ﷺ بها وجبت له الجنة
Its isnad is sahih. Muhajir Abu Hasan al-Sayigh al-Taymi, their freedman, is a well-known reliable narrator by his name, though no genealogy has been recorded for him, and his hadith appears in the Sahihayn.The hadith was narrated by Abu Dawud, 4/313, no. 5055, in the Book of Manners, chapter on what is said upon going to sleep, and by Tirmidhi, 5/474, no. 3403, in the Book of Supplications, chapter 22. Hakim graded it sahih, 1/565, and Dhahabi agreed with him.