Whenever a man embraced Islam, the first thing the Messenger of Allah ﷺ would teach us was the prayer, or he said, he would teach him the prayer.
كان رسول الله ﷺ إذا أسلم الرجل كان أول ما يعلمنا الصلاة أو قال: علمه الصلاة.
Bazzar (2765) narrated it, and this is his wording, and Tabarani in Al-Kabir (8/380), both through routes from Abu Malik Ashjai, from his father, who said, then he narrated it. Its chain is sahih. Abu Malik Ashjai's name is Saad bin Tariq bin Ashim. Haythami said in Al-Majmu (1/293), "Tabarani narrated it in Al-Kabir, and Bazzar, and its narrators are the narrators of the sahih." A similar version, with an addition that will come later in the chapter on supplications and remembrances, appears in Sahih Muslim (35:2697).