From Sahih Muslim (Hadith 6023):
Jabir b. 'Abdullah reported Allah's Messenger (ﷺ) as saying:In case we get wealth from Bahrain, I would give you so much and so much; he made an indication of it with both his hands. Allah's Apostle (ﷺ) died before wealth from Bahrain came, and it fell to the lot of Abu Bakr after him. He commanded the announcer to make announcement to the effect that he to whom Allah's Apostle (ﷺ) had held out promise or owed any debt should come (to him). I came and said: Allah's Apostle (ﷺ) had said to me: In case there comes to us the wealth of Bahrain I shall give you so much, and so much. Abu Bakr took a handful (of the coins) and gave that to me once and asked me to count them I counted them as five hundred dinars and he said: Here is double of this for you
Reference: Muslim 6023