What is derived from the saying of Allah the Exalted: "O you who believe, fear Allah and be with the truthful"

Question:
This brother, the questioner, says: In the noble verse I hope you will pause and explain what can be derived from this verse?

Answer:
Allah, Glorified and Exalted, said: This verse is from Surat al-Tawbah. It was revealed on the occasion of the Battle of Tabuk. The distance was far, and it was in the heat of summer, so none went out with the Prophet (peace and blessings be upon him) except the believers who were truthful in their faith. The hypocrites stayed behind.
They asked the Prophet (peace and blessings be upon him) to allow them to stay behind from the expedition, citing excuses they mentioned, and they were lying in that. The people of faith remained steadfast despite the long distance, the intense heat, and the pleasant fruits; they went out with the Messenger (peace and blessings be upon him), desiring the reward and obedience, may Allah be pleased with them. They returned safely, praise be to Allah. No fighting took place, because...
Because when the Romans heard of the Prophet's (peace and blessings be upon him) expedition toward them, and the departure of his Companions with him, they were seized with terror. So they stayed behind from the battle.
And Allah decreed its reward for the Muslim mujahideen with the Messenger (peace and blessings be upon him). It was the last battle the Messenger of Allah (peace and blessings be upon him) led. For this reason, Allah commanded His Prophet (peace and blessings be upon him) to say to the hypocrites: "You will never go out with me, nor will you fight an enemy with me. You were content to sit out the first time, so sit with those who sit out." Yes.