NASAI-KUBRA 10465:
from Ḥumayd b. ʿAbd al-Raḥman b. ʿAwf —
[Machine] "A group of the companions of the Prophet ﷺ told him that they heard the Messenger of Allah ﷺ saying, 'Say: He is Allah, [who is] One' [Surah Al-Ikhlas, verse 1]. It is equivalent to one-third of the Quran for those who recite it in their prayer."
الكبرى للنسائي ١٠٤٦٥:
عن حميد بن عبد الرحمن بن عوف —
أَنَّ نَفَرًا مِنْ أَصْحَابِ النَّبِيِّ ﷺ حَدَّثُوهُ أَنَّهُمْ سَمِعُوا رَسُولَ اللهِ ﷺ يَقُولُ {قُلْ هُوَ اللهُ أَحَدٌ} [الإخلاص 1] لَتَعْدِلُ ثُلُثَ الْقُرْآنِ لِمَنْ صَلَّى بِهَا
hadithunlocked.com