It is narrated from Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) that when the Messenger of Allah (peace and blessings be upon him) said the salam to end the prayer, he would recite these words: "Glorified is your Lord, the Lord of Might, above all that they (the polytheists) describe. And peace be upon all the Messengers. And all praise belongs to Allah alone, the Lord of all the worlds" [Surah al-Saffat: 180-182]. In another narration it is reported with these words: "More than once I heard the Messenger of Allah (peace and blessings be upon him) saying these same words at the end of his prayer, when he (peace and blessings be upon him) finished the prayer." And by yet another route the report is: "The Prophet (peace and blessings be upon him) used to recite this at the end of every prayer" (though the narrator was in doubt whether he (peace and blessings be upon him) said it after saying the salam or before the salam).
The narrator named Abu Harun is alone in transmitting this report, and he is da'if (weak, unreliable).
Hadith Referenceالمطالب العالية بزوائد المسانيد الثمانية / صفة الصلاة / 536
Hadith Gradingمحدثین:إسناده ضعيف
Hadith Takhrij«حکم الحدیث المطالب العالیہ محققاً تنسیق د. سعد بن ناصر بن عبد العزيز الشَّثري- مکتبہ شاملہ :قال ابن حجر: تَفَرَّدَ بِهِ أَبُو هَارُونَ وَهُوَ ضَعِيفٌ . » «أخرجه مصنف ابن أبي شيبة برقم: 3، وأخرجه إتحاف الخيرة المهرة بزوائد المسانيد العشرة برقم: 1390/1»