The Prophet ﷺ said, "When the prayer has been called to begin, no prayer is to be performed except the obligatory one."
حدثنا محمد بن جعفر قال حدثنا شعبة عن ورقاء عن عمرو بن دينار عن عطاء بن يسار
عن النبي ﷺ أنه قال إذا أقيمت الصلاة فلا صلاة إلا المكتوبة
Its isnad is sahih, previously mentioned at 8608. Warqa is Ibn Amr bin Kulayb, and the hadith was narrated by Muslim 1/493 number 710, Tirmidhi 2/282 number 421 who graded it hasan, Nasai 2/117, and Ibn Majah 1/364 number 1151.