The highest position in Paradise which will be attained by only one person is called al-Wasiilah. It will be attained, in shaa’ Allah, by the Chosen Prophet, the best of Allah’s creation our Prophet Muhammad, sallallahu alaihi wa sallam. In al-Nihayah, Ibn Kathir said:

"The highest position in Paradise was mentioned. It is al-Wasilah, which is the position of the Messenger of Allah, sallallahu `alaihi wa sallam."

This is also narrated in a hadith narrated by Bukhari from Jabir ibn `Abdullah, according to which the Prophet, sallallahu `alaihi wa sallam said:

"Whoever says, when he hears the call to prayer: ‘Allahumma Rabba haadhihi’d-da`wati’t-taammah, wa’s-Salati’l-qaa’imah aati Muhammadan al-wasiilah wa’l-faDiilah, wab`athhu maqaaman maHmoodan alladhii wa`adtah (O Allah, Rabb of this perfect Call, and the prayer to be offered, grant Muhammad al-Wasilah [the highest position in Paradise], and also the eminence, and resurrect him to the praised position You have promised),’ intercession for him will be granted on the Day of Resurrection."

Muslim reported that `Abdullah ibn `Amr ibn al-`As said:

"I heard the Messenger of Allah, sallallahu `alaihi wa sallam, say: ‘When you hear the muezzin call, say what he says, then send blessings on me, for whoever sends blessings on me, Allah will return it to him tenfold. Then ask Allah to grant me al-Wasilah, for whoever asks Allah to grant me al-Wasilah, intercession will be granted for him.’"

The Sahabah asked the Prophet, sallallahu `alaihi wa sallam: "What is al-Wasilah?" He said, "It is the highest level of Paradise, which only one man will reach, and I hope that I will be the one." This was reported by Ahmad from Abu Hurayrah; Ahmad also reported from Abu Sa`id that the Messenger of Allah, sallallahu `alaihi wa sallam, said:

"Al-Wasilah is a rank above which there is no other in the sight of Allah. Ask Allah to grant me Al-Wasilah." [See Ibn Kathir, Al-Nihayah, 2/2332]