Jami` at-Tirmidhi 1098
جامع الترمذي#1098SahihIbn Umar narrated that:The Messenger of Allah said: "Accept the invitation when you are offered
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Ahmad Muhammad ShakirSahih
Al-AlbaniSahih
Bashar Awad MaaroufHasan Sahih
Zubair Ali ZaiSahih - Agreed Upon
In-book reference: 11:19