Supplicating for someone saying 'May Allah extend your life'

Q 4: What is the ruling on saying to a person: "May Allah prolong your life"? Or "May Allah grant you a long life"? Does it contradict the perfection of Tawhid (belief in the Oneness of Allah) as Allah has already defined ages? Besides, what is ruling on saying to someone: "Accept my greetings.'' Is such a phrase specific to Allah (Glorified and Exalted be He)?

A: It is permissible to say to someone "May Allah prolong your life" or "May Allah grant you a long life". However, it is better to add: "... While you are in obedience to Allah" or even to intend it by heart. Similarly, it is permissible to say to someone: "Accept my greetings" as such a phrase is normally meant for greeting others. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.