Hadith #2343 (Sunan Ibn Majah)
Book: The Chapters on Legal Punishments
Narrator(s): Abu al-Juza' - Aws bin 'Abdullah أبو الجوزاء - أوس بن عبد الله الربعي, Abu Sa'id al-Khudri, Ahmed bin 'Ubda bin Musa أحمد بن عبدة بن موسى, Hammad bin Zayd حماد بن زيد بن درهم الأزدي الأزرق, Sulaiman bin 'Ali al-Rabi'y سليمان بن علي الربعي

“My maternal uncle passed by me – (one of the narrators) Hushaim named him in his narration as Harith bin Amr – and the Prophet (ﷺ) had given him a banner to carry. I said to him: ‘Where are you going?’ He said: ‘The Messenger of Allah (ﷺ) has sent me to a man who married his father’s wife after he died, and has commanded me to strike his neck (i.e. execute him).”

Source: https://parallelquran.com/hadith/sunan-ibn-majah-2343/