قَالَ ﷺ: «مَا مِنْ أحَدٍ يُسَلِّمُ عَلَيَّ، إلَّا رَدَّ اللهُ عَلَيَّ رُوْحي، حَتَّى أرُدَّ عَلَيْهِ السَّلامَ»

The Prophet \pbuh said: “Every time somebody greets me, Allāh gives me back my soul for me to answer this greeting.”

Reference: The Prophet \pbuh said: “Every time somebody greets me, Allāh gives me back my soul for me to answer this greeting.” Abū Dāwud (#2041). Al-Albānī declared it ḥasan in _Ṣaḥīḥ Abī Dāwud_ (1/283).