Sayyiduna Samurah or Uqbah (may Allah be pleased with them) narrates from the Prophet (peace and blessings be upon him) that he (peace and blessings be upon him) said: "The guarantee against a slave's defects is four days."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10754