Abdullah bin Umar reported,
I saw the Messenger of Allah ﷺ more than twenty-five times, or more than twenty times—Abdul-Razzaq said, "I am the one who is uncertain"—reciting in the two rakahs of Fajr, "Say, O you disbelievers" and "Say, He is Allah, the One."
Ahmad 4909
Sahihحدثنا عبد الرزاق أخبرنا الثوري عن أبي إسحاق عن مجاهد
عن ابن عمر قال
رأيت رسول الله ﷺ أكثر من خمس وعشرين مرة أو أكثر من عشرين مرة قال عبد الرزاق وأنا أشك يقرأ في ركعتي الفجر قل يا أيها الكافرون و قل هو الله أحد
Its isnad is sahih, and it is a shortened version of 
4763 through the route of Israil from Abu Ishaq. We already mentioned there Tirmidhi's statement that he does not know it from the narration of Thawri from Abu Ishaq except through the hadith of Abu Ahmad Zubayri. This isnad refutes that claim, and shows that Abu Ahmad Zubayri was not alone in narrating it from Thawri from Abu Ishaq, for here it comes through the narration of Abdul-Razzaq from Thawri from Abu Ishaq.