Shaykh Rabee – May Allaah preserve him – said:
The Messenger of Allaah ﷺ singled out the ten to be the most virtuous of the companions (May Allaah be pleased with them): “Abu Bakr is in Jannah, and Umar is in Jannah, and ‘Uthman is in Jannah, and Ali is in Jannah, and Talhah is in Jannah, and Az-Zubayr is n Jannah, and Abdur-Rahmaan ibn ‘Awf is in Jannah, and Sa’d Ibn Abee Waqqaas is in Jannah, and Sa’eed Ibn Zayd ibn ‘Umayr ibn Nufayl is in Jannah and Abu Ubaidah ibn Al-Jarrah is in Jannah.(Ref: 1)
Then these ten are those famous in the Ummah due to it being known that they have been granted entrance into paradise. The Messenger of Allaah ﷺ bore witness to that for them and this virtue is one that is specific to the Ten (May Allaah be pleased with them).
[SOURCE: AN EXCERPT FROM AL-WASAAYAA AL-MANHAJIYYAH LI MUTTABI’I AHLUS-SUNNAH AN-NABAWIYYAH PG.223. slightly paraphrased]
Ref 1: Reported by Imaam Ahmad (rahimahullaah) his Musnad (1/194) and At-Tirmidhee in Al-Manaaqib Al-Hadeeth (no.3747).