Sent to Yemen

Sending someone to Yemen was not like sending someone to a nearby tribe. It was a long way off, it had a settled population with its own religious communities, and whoever went would be out of contact for long stretches and would have to decide things alone.

The Prophet ﷺ gave Mu'adh instructions before he left, and they are worth noticing for their order.

Call them to the oneness of Allah first. If they accept that, tell them about the prayer. If they accept that, tell them about the charity due from the wealthy among them, to be returned to the poor among them.

One thing at a time, in sequence, each step waiting on the one before it. He was not told to arrive and impose the whole of it at once.

Two further instructions came with it. Take from the charity what is due and not the best of people's property — the thing they would most mind losing. And be wary of the supplication of a person who has been wronged, because there is nothing between it and Allah.

That last one is addressed to a man being given power over others. He is being told, before he leaves, that the people he will have authority over have a recourse he cannot block.

The instructions are reported in both Sahih collections. Mu'adh was still in Yemen when the Prophet ﷺ died.