Narrated 'Aishah:
That the Messenger of Allah (ﷺ) advanced towards Badr till he reached Harrah Al-Wabr where he was met by a man from the idolaters, about whom it was said he was brave and courageous. The Prophet (ﷺ) said to him: Do you believe in Allah and his Messenger? He said: No. He said: Then return, because we do not seek aid from an idolater.
The Hadith has more dialogue than this. And this is a Hasan Gharib Hadith. This is acted upon according to some of the people of knowledge. They say that the people of Adh-Dhimmah do not recieve a share, even it they were to fight along with the Muslims against the enemy.
Some of the people of knowledge said that they are given a share when they attend the battle with the Muslims.
It has been related by Az-Zuhri, that the Prophet (ﷺ) gave a portion to some people among the Jews who fought along with him. This was narrated to us by Qutaibah (who said):
Abdul-Warith bin Sa'eed narrated to us from 'Urwah bin Thabit, from Az-Zuhri.
This Hadith is Hasan Gharib.