Sunan an-Nasa'i 4196
سنن النسائي#4196SahihAbu Hurairah narrated that the Messenger of Allah said:"The Imam is like a shield whose orders should be obeyed when they (the Muslims) fight, and where they should seek protection. If he enjoins fear of Allah and behaves justly, then he will be rewarded, but if he enjoins otherwise, then it will be a burden (of sin) on him
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiSahih - Agreed Upon
In-book reference: 39:48