Jami at-Tirmidhi 403
Jami at-Tirmidhi · Book 2: The Book on Salat (Prayer) · [What Has Been Related] About Not Performing The Qunut
There is another narration from Abu Malik:
حَدَّثَنَا صَالِحُ بْنُ عَبْدِ اللَّهِ ، حَدَّثَنَا أَبُو عَوَانَةَ ، عَنْ أَبِي مَالِكٍ الأَشْجَعِيِّ ، بِهَذَا الإِسْنَادِ نَحْوَهُ بِمَعْنَاهُ .
There exists another narration from Abu Malik with similar meaning but with different chain.
Grade: Sahih (Darussalam)