Amr ibn Al-‘As was commander of the army sent to conquer Egypt during the Caliphate of Umar ibn al-Khattab. After the conquest Amr became Egypt's first Islamic governor (wali).
The Muslim forces laid siege to the Babylon Fortress in 641CE (in the area known as Coptic Cairo today) where al-Muqawqis, the Egyptian Ruler was holed up. General Amr ibn Al-‘As sent a delegation of ten men, headed by Ubadah ibn as-Samit, to speak with al-Muqawqis.
Ubadah was black, and when the delegation travelled by boat to al-Muqawqis and entered his place, Ubadah stepped forward and al-Muqawqis was alarmed because of his blackness.
He said, "Take this black man away from me and let someone else come and speak to me!"
They said, "This black man is the best of us in knowledge and wisdom. He is our leader and the best of us, and has been appointed over us. We all refer to his opinion, and our leader has appointed him over us and ordered us not to go against him."
Al-Muqawqis said to the delegation, "How could you accept this black man as the best among you? Rather he should be the least among you."
They said, "No; even though he is black as you can see, he is the best in status among us, one of the foremost among us and one of the wisest. Blackness is not something bad among us."
Al-Muqawqis said to Ubadah, "Come forward, O black man, and speak to me gently, for your blackness alarms me, and if you speak harshly that will alarm ne further."
Ubadah went forward and said, "I have heard what you said. Among my companions whom I left behind are a thousand men who are all as black as me, and even blacker than me and more terrifying to behold. If you saw them you would be even more alarmed. My youth has gone, but nevertheless I would not be scared if one hundred men of my enemy wanted to face me all at once, and the same is true of my companions, for our hope and our desire is to strive in jihad for the sake of Allah, seeking the pleasure of Allah.
The reason for our campaign against our enemies who wage war against Allah is not hope of worldly gains or the accumulation of wealth; rather Allah has permitted that to us and made the booty we acquire permissible for us. But none of us cares whether he has a qintar of gold or has nothing but a dirham, because all we want from this world is something to eat and ward off hunger, and a cloth to wrap around ourselves. If one of us owns nothing more than that, that is enough. If he gets a qintar of gold he will spend it for the sake of Allah and be content with the little that is left in his hand, because the pleasure of this world is not true pleasure and its luxury is not true luxury; rather real pleasure and luxury come in the Hereafter.
This is how our Lord has guided us and our Prophet has taught us; he advised us that our ambition in this world should be just to have enough to ward off hunger and cover our awrahs (nakedness); our main concern should be to please our Lord and strive in jihad against His enemies."
When al-Muqawqis heard that, he said to those who were around him: "Have you ever heard anything like what this man is saying? His appearance alarmed me but his words alarm me more than his appearance. Allah has sent this man and his companions out to destroy the world! I think that they are bound to prevail over the entire world."
Dr Ali Muhammad as-Sallabi, ‘Umar ibn al-Khattab his life and times,' Vol. 2, p. 327