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) said: "Whoever comes to me as a visitor, having no purpose other than visiting me, it is a right upon me that I be his intercessor on the Day of Resurrection."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 13092