Hishaam ibn al-‘Aas al-Umayee (radhiyallahu anhu) said:
“I and another man was sent to Heraclius, the Emperor of Rome, to give him Dawah (invitation) to Islam. We set out until we arrived at al-Ghouta, meaning Damascus, whereupon we went down to (see) Jabalah ibn al-Ayham al-Gassaani (the king there appointed by Rome). We entered (his palace) while he was in his bed, so he sent his messenger to us for us to speak to.
“By Allah! We will not speak to a messenger. We have been sent only to the King. If he permits us, we shall speak to him, but we will not speak to the Messenger.”
So the messenger returned to him and informed him with this. Then he (the king) gave us permission and said:
So Hishaam ibn al-‘Aas spoke to him and gave him Dawah to Islam. Lo and behold, he (the king) was wearing black clothes (in entirety), so Hisham said to him:
“What is (the deal with) these (black clothes) upon you?”
“I am wearing them (because of you), and I swore never to remove them until I expel you (lot) from Syria!”
“This very sitting place of yours, by Allah, we shall (soon) seize from you, and we shall (also) seize the kingdom of your great king (i.e. Heraclius), by the Will of Allah! Our Prophet, Muhammad (sallallahu alayhi wasallam), informed us of this.”
“You are not those (people who will conquer us). Rather, they (who will conquer us) will be a people who fast during the days and remain standing during the nights (for prayer).”
(Recorded in the Tafseer of Ibn Katheer who commented that there are no problems with the chain)
The Romans had seen in their scriptures, which still contained much truth, the prophecies describing those people who will eventually conquer them. The lengthy narration goes onto mention that when the king was apprized of the fact that these men (i.e. the Sahabah radhiyallahu anhum) did indeed possess these qualities (i.e. the habit of fasting during the days and remaining standing during the nights), his face grew intensely dark.
تفسير ابن كثير
ﻭﻗﺎﻝ اﻟﺤﺎﻛﻢ ﺻﺎﺣﺐ اﻟﻤﺴﺘﺪﺭﻙ ﺃﺧﺒﺮﻧﺎ ﻣﺤﻤﺪ ﺑﻦ ﻋﺒﺪ اﻟﻠﻪ ﺑﻦ ﺇﺳﺤﺎﻕ اﻟﺒﻐﻮﻱ ﺣﺪﺛﻨﺎ ﺇﺑﺮاﻫﻴﻢ ﺑﻦ اﻟﻬﻴﺜﻢ اﻝﺑﻞﺩﻱ ﺣﺪﺛﻨﺎ ﻋﺒﺪ اﻟﻌﺰﻳﺰ ﺑﻦ ﻣﺴﻠﻢ ﺑﻦ ﺇﺩﺭﻳﺲ ﺣﺪﺛﻨﺎ ﻋﺒﺪ اﻟﻠﻪ ﺑﻦ ﺇﺩﺭﻳﺲ ﻋﻦ ﺷﺮﺣﺒﻴﻞ ﺑﻦ ﻣﺴﻠﻢ ﻋﻦ ﺃﺑﻲ ﺃﻣﺎﻣﺔ اﻟﺒﺎﻫﻠﻲ ﻋﻦ ﻫﺸﺎﻡ ﺑﻦ اﻟﻌﺎﺹ اﻷﻣﻮﻱ ﻗﺎﻝ ﺑﻌﺜﺖ ﺃﻧﺎ ﻭﺭﺟﻞ ﺁﺧﺮ ﺇﻟﻰ ﻫﺮﻗﻞ ﺻﺎﺣﺐ اﻟﺮﻭﻡ ﻧﺪﻋﻮﻩ ﺇﻟﻰ اﻹﺳﻼﻡ ﻓﺨﺮﺟﻨﺎ ﺣﺘﻰ ﻗﺪﻣﻨﺎ اﻟﻐﻮﻃﺔ ﻳﻌﻨﻲ ﻏﻮﻃﺔ ﺩﻣﺸﻖ ﻓﻨﺰﻟﻨﺎ ﻋﻠﻰ ﺟﺑﻞﺓ ﺑﻦ اﻷﻱﻫﻢ اﻟﻐﺴﺎﻧﻲ ﻓﺪﺧﻠﻨﺎ ﻋﻠﻴﻪ ﻓﺈﺫا ﻫﻮ ﻋﻠﻰ ﺳﺮﻳﺮ ﻟﻪ ﻓﺄﺭﺳﻞ ﺇﻟﻴﻨﺎ ﺑﺮﺳﻮﻟﻪ ﻧﻜﻠﻤﻪ ﻓﻘﻠﻨﺎ ﻭاﻟﻠﻪ ﻻ ﻧﻜﻠﻢ ﺭﺳﻮﻻ ﻭﺇﻧﻤﺎ ﺑﻌﺜﻨﺎ ﺇﻟﻰ اﻟﻤﻠﻚ، ﻓﺈﻥ ﺃﺫﻥ ﻟﻨﺎ ﻛﻠﻤﻨﺎﻩ ﻭﺇﻻ ﻟﻢ ﻧﻜﻠﻢ اﻟﺮﺳﻮﻝ ﻓﺮﺟﻊ ﺇﻟﻴﻪ اﻟﺮﺳﻮﻝ ﻓﺄﺧﺒﺮﻩ ﺑﺬﻟﻚ. ﻗﺎﻝ: ﻓﺄﺫﻥ ﻟﻨﺎ ﻓﻘﺎﻝ: ﺗﻜﻠﻤﻮا ﻓﻜﻠﻤﻪ ﻫﺸﺎﻡ ﺑﻦ اﻟﻌﺎﺹ ﻭﺩﻋﺎﻩ ﺇﻟﻰ اﻹﺳﻼﻡ ﻓﺈﺫا ﻋﻠﻴﻪ ﺛﻴﺎﺏ ﺳﻮﺩ ﻓﻘﺎﻝ ﻟﻪ ﻫﺸﺎﻡ ﻭﻣﺎ ﻫﺬﻩ اﻟﺘﻲ ﻋﻠﻴﻚ؟ ﻓﻘﺎﻝ ﻟﺒﺴﺘﻬﺎ ﻭﺣﻠﻔﺖ ﺃﻥ ﻻ ﺃﻧﺰﻋﻬﺎ ﺣﺘﻰ ﺃﺧﺮﺟﻜﻢ ﻣﻦ اﻟﺸﺎﻡ ﻗﻠﻨﺎ ﻭﻣﺠﻠﺴﻚ ﻫﺬا ﻭاﻟﻠﻪ ﻟﻨﺄﺧﺬﻧﻪ ﻣﻨﻚ ﻭﻟﻨﺄﺧﺬﻥ ﻣﻠﻚ اﻟﻤﻠﻚ اﻷﻋﻈﻢ ﺇﻥ ﺷﺎء اﻟﻠﻪ، ﺃﺧﺒﺮﻧﺎ ﺑﺬﻟﻚ ﻧﺒﻴﻨﺎ ﻣﺤﻤﺪ ﺻﻠﻰ اﻟﻠﻪ ﻋﻠﻴﻪ ﻭﺳﻠﻢ ﻗﺎﻝ: ﻟﺴﺘﻢ ﺑﻫﻢ ﺑﻞ ﻫﻢ ﻗﻮﻡ ﻳﺼﻮﻣﻮﻥ ﺑﺎﻟﻨﻬﺎﺭ ﻭﻱﻗﻮﻡﻭﻥ ﺑﺎﻟﻠﻴﻞ