The highest position in Paradise which will be attained by only one person is called al-Waseelah. It will be attained, insha’Allah, by the Chosen Prophet, the best of Allah’s creation, our Prophet Muhammad (saw).
This is narrated in a hadith narrated by al-Bukhaari from Jaabir ibn ‘Abdullaah according to which the Prophet (saw) said, “Whoever says, when he hears the call to prayer, “Allahumma Rabba hadhihi-da’wati-tammah, was-salaatil-qaa’imah, aati muhammadan al-waseelata wal-fadeelata, wab’aththu maqaaman mahmoodan alladhi wa’adtahu [O Allah, Lord of this Perfect Call and the Prayer to be Offered, grant Muhammad al-Waseelah – 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 ‘Abdullaah ibn ‘Amr al-‘Aas said, “I heard the Messenger of Allah (saw) say, “When you hear the muaddhin call, say what he says, then send blessings on me, for whoever sends blessings on me, Allah (swt) will return it to him tenfold. Then ask Allah to grant me al-Waseelah, for whoever asks Allah (swt) to grant me al-Waseelah intercession will be granted for him.””
The Sahaabah asked the Prophet (saw) “What is al-Waseelah?” He said, “It is the highest level of Paradise, which only one man will reach, and I hope that I will be the one”. [Ahmad from Abu Hurayrah]
The Messenger of Allah (saw) said, “al-Waseelah is a rank above which there is no other in the sight of Allah (swt). Ask Allah (swt) to grant me al-Waseelah” [Ahmad from Abu Sa’eed, See Ibn Katheer, an-Nihaayah, 2/2332]