It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) heard Sayyiduna Umar bin Al-Khattab (may Allah be pleased with him) swear by his father in a caravan, so he said: "Indeed, Allah Almighty forbids you from swearing by your forefathers. So now, whoever wants to swear an oath, let him swear by Allah, otherwise let him remain silent."
Hadith Referenceسنن دارمي / من النذور و الايمان / 2378
Hadith Gradingتحقیق (حسین سلیم أسد الدارانی):إسناده صحيح والحديث متفق عليه، [مكتبه الشامله نمبر: 2386]