Sayyiduna Abu Hurairah (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) said: "When one of you," or he said: "When a man gets up from his place (for some need) and then returns, he has more right to that place."
Hadith Referenceسنن دارمي / من كتاب الاستئذان / 2689
If a person stands up from his place for some need with the intention of returning, then upon his return, he has the greatest right to that spot. If another person sits there, he should vacate it for him. And Allah knows best.