Imam Malik (may Allah have mercy on him) was asked about the saying of the Prophet (peace and blessings be upon him): "A day and a night is hospitality," and he said: For a day and a night he should honour him, give him gifts and look after him, and hospitality is for three days.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجزية / 18690