In the well-known hadith narrated by Abū Bakr from the Prophet, may Allah bless him and grant him peace, he said:

“Ask Allah for certainty and well-being, for after certainty no one has been given anything better than well-being. So ask Allah for both.”

Those who possess certainty remain steadfast when tested, unlike others, whose faith may be lost or diminished through trials. Allah Most High says:

“And We made from among them leaders guiding by Our command, when they were patient and had certainty in Our signs.”

Do you not see His words:

“Those to whom people said, ‘People have gathered against you, so fear them.’ But this increased them in faith, and they said, ‘Allah is sufficient for us, and He is the best Disposer of affairs.’”

Such was their state. Allah Most High also says:

“O you who believe, remember Allah’s favour upon you when armies came against you, and We sent against them a wind and armies you did not see. And Allah sees all that you do.”

The passage continues to His words:

“There the believers were tested and shaken severely.”

“And when the hypocrites and those in whose hearts is disease said, ‘Allah and His Messenger promised us nothing but delusion.’”

Allah Most High also says, in the two verses:

“We have appointed none but angels as guardians of the Fire, and We have made their number only a trial for those who disbelieve, so that those given the Scripture may attain certainty.”

As for how certainty is attained, it is through three things:

The first is reflecting upon the Quran.

The second is reflecting upon the signs Allah brings about within human beings and across the horizons, which show that it is the truth.