Sunan Ibn Majah
3276
Sahih+2

It was narrated that Wathilah bin Asqa’ Al-Laithi said:“The Messenger of Allah (ﷺ) took hold of the top of the Tharid and said: ‘Eat in the Name of Allah from its sides and leave the top, for the blessing comes from its top.’”

SahihAl-Albani
SahihMuhammad Fouad Abd al-Baqi