"If you do not aid the Prophet - Allah has already aided him when those who disbelieved had driven him out [of Makkah] as one of two, when they were in the cave and he said to his companion, "Do not grieve; indeed Allah is with us." And Allah sent down his tranquillity upon him and supported him with angels you did not see and made the word of those who disbelieved the lowest, while the word of Allah - that is the highest. And Allah is Exalted in Might and Wise."
This Verse has no praise to the person who was with the Prophet in the cave. In fact it has negative points against him.
1. He was feeling sad despite being with the Prophet in the same place, which was wrong feeling and the Prophet told him: Do not grieve. He was wrong in grieving.
2. Allah sent His tranquility on the Prophet only and not on that person which means that he was not entitled to get the tranquility from Allah. Allah mentioned in Quran that: He sent tranquility on the believers. (Al-Fath, 4).
It worth mentioning that there is no authentic evidence that the person was Abu Bakr, on the contrary there are Hadeeths in Sunni books that Ab Bakr was in Madina during the journey of the Prophet from Makkah to Madina.
There is nice books written by Shaikh Najaah Al-Taa'ee in this subject.
Many Sunni scholars have stated that this verse does not have praise to the person who was with the Prophet in the cave.