Hadith 1119
'Ali bin Abu Talib (May Allah be pleased with him)reported:
عن علي بن أبي طالب، رضي الله عنه قال كان النبي صلى الله عليه وسلم يصلي قلب العصر أربع ركعات يفصل بينهن بالتسليم على الملائكة المقربين ومن تبعهم من المسلمين والمؤمنين. رواه الترمذي وقال حديث حسن.
The Prophet (ﷺ) used to perform four Rak'ah before the 'Asr prayer, separating them with Taslim (i.e., offering blessings) on the favourite angels who are near Allah's proximity and the Muslims and the believers who come after them. [At- Tirmidhi].
In plain words
Ali reports that the Prophet used to pray four units before the Asr prayer, with the closing greeting, sending blessings on the angels near Allah and on the believers who follow.
Reference : Riyad as-Salihin 1119 In-book reference : Book 8, Hadith 129