Saeed bin Jubair (may Allah have mercy on him) said: "In the time of ignorance, a man would make a pact with another, and both would become heirs to each other."
Hadith Referenceسنن سعید بن منصور / كتاب ولاية العصبة / 1435
Hadith Takhrij«أخرجه سعيد بن منصور فى «سننه» ترقيم الدرالسلفية برقم: 258، 625»