Thumamah ibn Uthal (Arabic: ثمامة بن أثال) was chieftain of the Banu Hanifah and one of the rulers of al-Yamamah, making him among the most powerful Arab rulers in pre-Quranic times. In 628 Muhammad sent eight letters to rulers in the Arabian peninsula and surrounding areas inviting them to Islam, including Thumamah. After receiving the letter, he was consumed by anger and resolved to kill Muhammad.
In the pursuit of his designs Thumamah killed a group of Muhammad's companions. Not long afterwards, Thumamah left al-Yamamah to perform umrah in Mecca and was apprehended by a group of Muslims patrolling the areas surrounding Medina. Unaware of who he was they tied him to a column in the mosque and waited for Muhammad to decide his fate. Muhammad approached Thumamah hoping to encourage him to become a Muslim, but after his refusal he was allowed to leave. Thumamah rode until he came to a palm grove on the outskirts of Medina near al-Baqi' where he watered his camel and washed himself. Then he turned back to Muhammad's mosque and proclaimed his acceptance of Islam, plegding himself and those with him in the service of Muhammad.
Muhammad then told him to continue with his plans and perform umrah as prescribed in Islamic rites. When he reached the valley of Mecca, he began shouting in a resonant voice: "Here I am at Your command O Lord, Here I am. Here I am. No partner have You. Here I am. Praise, bounty and Dominion belong to You. No partner have You."
He was thus the first Muslim to enter Mecca reciting the talbiyah. The Quraish heard him and set out to punish the one who had assaulted their preserve. One of them was particularly incensed and was about to shoot Thumamah with an arrow when the others grabbed him and shouted: "Woe to you! Do you know who this is? He is Thumamah ibn Uthal, ruler of al-Yamamah. By God, if you should harm him, his people would cut our supplies, with dire consequences for us."
Thumamah finished performing umrah and proclaimed that he followed the religion of Muhammad. He then returned to his land and ordered his people to withhold supplies from the Quraish. The boycott gradually began to have effect, raising prices and causing many to go hungry. Thereupon, the Quraish wrote to Muhammad, asking him to instruct Thumamah to lift the boycott as it violated the treaty of Hudaybiyyah, which he did.
When Muhammad died in 632, many Arabs began leaving Islam in great numbers. Musaylamah began calling the Banu Hanifah to believe in him as a prophet. Thumamah confronted him gathered together all those who had remained Muslims and waged jihad against the apostates. The loyal Muslims of Banu Hanifah needed additional help to stand against the armies of Musaylamah. Their arduous task was completed by the forces dispatched by Abu Bakr but at the cost many Muslim lives.