Whoever prays in the mosque of the Messenger of Allah, I heard the Messenger of Allah ﷺ say, "A prayer in it is better than a thousand prayers in any other mosque, except the mosque of the Kaabah."
أخبرنا قتيبة قال حدثنا الليث عن نافع عن إبراهيم بن عبد الله بن معبد بن عباس أن
من صلى في مسجد رسول الله فإني سمعت رسول الله ﷺ يقول الصلاة فيه أفضل من ألف صلاة فيما سواه إلا مسجد الكعبة
Ahmad narrated it, 6/334, hadith 27374, from the hadith of Layth bin Saad with the same chain, and it is also in Kubra, hadith 770. Muslim also narrated it in the book of Hajj, chapter on the merit of prayer in the two mosques of Makkah and Madinah, hadith 1396, from Qutayba with the same chain, except that he said, "from Ibrahim bin Abdullah bin Mabad, from Ibn Abbas," and this is also found in one of the manuscript copies of Nasai.