Anas bin Malik reported the Apostle of Allaah(ﷺ) as saying “ I am commanded to fight with the polytheists. The rest of the tradition is to the same effect as mentioned above.”
Sunan Abi Dawud Book 15, Hadith 166
← Previous Hadith The Prophet (ﷺ) said: I am commanded to fight with men till they testify that there is no god but Allah, and that Muhammad is His servant and His Apostle, face our qiblah (direction of prayer), eat what we slaughter, and pray like us. When they do that, their life and property are unlawful for us except what is due to them. They will have the same rights as the Muslims have, and have the same responsibilities as the Muslims have.

Sunan Abi Dawud Book 15, Hadith 165 Next Hadith → Usamah bin Zaid said “The Messenger of Allah (ﷺ) sent us with a detachment to Al Huruqat. They learnt about us and fled away. But we found a man, when we attacked him he uttered “There is no god but Allaah, still we struck him till we killed him.” When I mentioned it to the Prophet (ﷺ) he said “Who will save you from “There is no god but Allaah” on the Day of Judgment? I said “Messenger of Allah (ﷺ), he uttered it for the fear of the weapon.” He said “Did you tear his heart so that you learnt whether he actually uttered it for this or not. Who will support you against “There is no god but Allaah”? He kept on repeating this till I wished I would have embraced Islam on that day.

Sunan Abi Dawud Book 15, Hadith 167