How does the Prophet (peace be upon him) respond to the millions of prayers of his Ummah upon him simultaneously, and how does he water this vast number at the Hawd (Pond)?

Our prayers and salutations upon the Prophet, peace and blessings be upon him, reach him. Ibn Mas'ud reported that angels convey the greetings of his Ummah to him. And Abu Hurayrah reported that there is no one who sends salutations upon him except that Allah restores his soul to him so that he may return the salutation. The states of the Barzakh (interim realm) are among the unseen matters that we believe in without delving into their modality. And the Prophet's returning salutations to millions of Muslims is not too much for Allah's power.