Shaikh Saleem al-Hilali hafidhuhallah wrote:
“Allah looked at the hearts of the Companions of the Messenger of Allah sallahu alayhi wa salam and He found their hearts the best hearts of the servants after the heart of Muhammad sallahu alayhi wa sallam. So, He gave them understanding which those after them could not realize/obtain. So like that, what the Companions saw as good is good in the sight of Allah and what the Companions saw as evil is evil in the sight of Allah.
Abdullah Ibn Mas’ud radiallahu anhu said: “Verily, Allah looked at the hearts of the servants and He found that the heart of Muhammad, peace and blessings be upon him, was the best among them, so He choose him for Himself and He sent him with His message. Then, He looked at the hearts of His servants after Muhammad, and He found that the hearts of his companions were the best among them. Thus, He made them into the ministers of His Prophet, fighting for the sake of His religion. And whatever the Muslims view as good is good in the sight of Allah, and whatever they view as evil is evil in the sight of Allah”
[Reported in Ahmad (1/379), Tayalisi in his Musnad (pg. 23), Khateeb in al-Faqeeh wal-Mutafaqqih (1/166). Its chain is Jayyid Mawqoof]
On the authority of Abu Juhaifah who said:
I asked `Ali “Do you have anything (in regards to) divine literature besides what is in the Qur’an?” `Ali said, “By Him Who made the grain split (germinate) and created the soul, we have nothing except what is in the Qur’an and the ability (gift) of understanding Allah’s Book which He may endow a man, with and what is written in this sheet of paper.” I asked, “What is on this paper?” He replied, “The legal regulations of Diya (Blood-money) and the (ransom for) releasing of the captives, and the judgment that no Muslim should be killed in Qisas (equality in punishment) for killing a Kafir (disbeliever).
[Reported in Bukhari no. 111]
So like that, the Companions understanding of the Book and the Sunnah is evidence for those after them until the end of this Ummah. So like that, they are the witnesses of Allah on the earth”
[Taken from: Basaair Dhawil-Sharf bi Sharh Marwiyaat Manhaj Salaf pg. 63-64]
Faisal Ibn Abdul Qaadir Ibn Hassan