Sayyiduna Umar (may Allah be pleased with him) said: I heard the Messenger of Allah (peace and blessings be upon him) say: "Whoever visits my grave" or he said: "Whoever visits me, I will be an intercessor or a witness for him. And whoever dies in one of the two Sanctuaries, Allah will raise him among those who are safe on the Day of Resurrection."
This chain is majhul (contains an unknown narrator).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 10273