The Prophet ﷺ used to break his fast before praying with fresh dates. If fresh dates were not available, then with dried dates. If dried dates were not available, he would take a few sips of water.
حدثنا محمد بن رافع حدثنا عبد الرزاق أخبرنا جعفر بن سليمان عن ثابت
كان النبي ﷺ يفطر قبل أن يصلي على رطبات فإن لم تكن رطبات فتميرات فإن لم تكن تميرات حسا حسوات من ماء
[Its isnad is hasan]. Abu Dawud also narrated it, no. 2356 (see the previous hadith), from the hadith of Abdul-Razzaq through this route. Daraqutni graded it sahih, 2/185, and Hakim said it meets the criteria of Muslim, 10/422, and Dhahabi agreed with him.