From Sahih Muslim (Hadith 5368):
Jabir b. 'Abdullah reported:I heard Allah'. s Messenger (ﷺ) as saying: Food for one person suffices two persons and food for two persons suffices four persons, and food for four persons suffices eight persons; and in the tradition transmitted on the authority of Ishaq there is no mention of the fact that he heard it directly (from the Holy Prophet)
Reference: Muslim 5368