Who was the Companion whom the Messenger of Allah, peace and blessings be upon him, sent to kill one of the symbols of disbelief, and who then hid in a cave over whose entrance a spider had woven its web?

The Companion in question is Abdullah ibn Unays al-Juhani. The Prophet, peace and blessings be upon him, sent him to kill Sufyan ibn Khalid al-Hudhali, who was gathering forces to fight the Muslims. The Prophet described Sufyan to him, saying that if Abdullah saw him, he would be awestruck and intimidated by him. Abdullah ibn Unays set out disguised, and after reaching Sufyan, he managed to kill him and take his head. He then hid in a cave, and a spider wove a web over the entrance of the cave, protecting him from his pursuers, who did not find him. This story is mentioned in multiple sources. The narrations by Imam Ahmad and Abu Dawud mention the story without the detail of the spider.