Sunan Abu Dawud
762
Sahih Maqtu+2

Shu’aib b. Abi Hamzah said:Ibn al-Munkadir, Ibn Abi Farwah and a number of jurists of Madina said to me: When you recite the supplication “I am first of the Muslims,” say instead; “I am one of the Muslims”

Sahih MaqtuAl-Albani
Sahih MaqtuMuhammad Muhyi Al-Din Abdul Hamid