According to akhbarelyom.com, the origin story of the idiom started with a wealthy man that lost his wealth, who was later invited by another man to stay with him. The man bought apricots for his family and the wealthy man ate only 3. However, the following day, the man bought grapes and the wealthy man ate them all without accounting for the man’s family and kids. Surprised, he asked him to leave some for them, but the wealthy man replied with “لا ده في المشمش”, referring to how apricots are larger in size so he ate a fewer amount, thus there's more to share, in contrary to eating larger amounts of little grapes.
