Question: Is it fard (obligatory, a commandment) to believe in the Sirat Bridge?
ANSWER
Yes, it is fard to believe in it, for it is established by the Nass, that is, the Qur'an and ahadith. The Qur'an al-karim says (what means):
(Take them to the Sirat of Hell and imprison them because they are accountable.) [As-Saffat 23, 24]

It is written in the book Nuhbat-ul-La'ali:
The Sirat is a bridge over Hell. A Qur'anic verse says (what means):
(There is none among you who will not come to it [Hell].) [Maryam 71]

It is stated in hadith-i sharifs:
(The Sirat Bridge will be set over Hell. The first prophet who will cross it with his nation will be I.) [Bukhari]

(On the Day of Resurrection I will stand by the side of the Sirat Bridge and wait for my nation to cross it. Allahu ta'ala will say, "Ask for whatever you want. Intercede for whomever you wish, for your intercession will be accepted." After interceding for my nation, I will continue entreating, and I will not rise to my feet until He says, "Put all people into Paradise who said La ilaha ill-Allah once with ikhlas and died with faith.) [Imam-i Ahmad]

(Crossing the Sirat Bridge depends on everybody's light. Some will cross it in the twinkling of an eye; some, like lightning; some, like a falling star; some, like a running horse. He who has very little light will creep facedown. His hands and feet will slip, and he will cling to it again. At long last, he will break free from it by creeping and creeping.) [Tabarani]

(Whoever loves my Ahl-i Bait and companions much, his feet will not slip when he crosses the Sirat Bridge.) [Daylami]

(None of the holders of bid'a will be able to cross the Sirat. They will fall into Hell.) [Ibn 'Asakir]

(Hellfire will say to Believers, "O the Believer! Pass over me quickly, for your light is extinguishing my fire.") [Tabarani]

(Many people will not know that they crossed the Sirat and will ask angels, "Where are the Sirat and Hell? Did we cross them?" Angels will answer, "You crossed the Sirat, which was over Hell. However, Hellfire receded and was covered because of your light.") [Jami'us-saghir]

Some people from the nation of our master the Prophet will go directly to Paradise after rising from their graves. Angels will say to them:
"Were you called to account?"
"No, we did not go through any accounting."
"Did you cross the Sirat Bridge?"
"No, we did not see it."
"Did you see Hell?"
"No, we did not see it, either."
"What deed did you do that you came directly to Paradise without being called to account and crossing the Sirat?"
"We did possess two traits, whereby we have attained this blessing: We were ashamed of Allah and did not use to commit sins in private, either. Secondly, we used to be pleased with a little sustenance that Allah gave us."
Angels will say, "These blessings are your due." (Ibn Hibban)

When mentioning the Sirat Bridge, we should not suppose that it is like bridges that we know. As a matter of fact, we say that it is necessary to pass the bridge of examination in order to pass the course. However, an examination is, in no way, similar to a bridge. Similarly, the Sirat Bridge is, in no way, like worldly bridges or the bridge of examination. (Endless Bliss)

The questions to be asked
Question: What are the questions to be asked at the Sirat Bridge?
ANSWER
Seven questions will be asked at seven places at the Sirat Bridge:
The first question will be about faith (iman). If one's faith is correct, one will pass the first station. If not, one will fall into Hell.

The question to be asked at the second station will be about salat (namaz). It is declared in hadith-i sharifs:
(Salat is the most virtuous of all deeds that Allahu ta'ala is pleased with. It is a light in the grave and something that makes one cross the Sirat Bridge like lightning.) [Miftah-ul-Janna]

(The first thing one will be questioned about on the Day of Resurrection will be salat. If one's salat is found satisfactory, one's other deeds will be accepted. If one's salat is not found satisfactory, none of one's deeds will be accepted.) [Tabarani]
[For this reason, every Muslim must perform salat, which is the pillar of the religion. There is no building without a pillar. There are many hadith-i sharifs stating that those who take salat lightly will become disbelievers.]

The question to be asked at the third station will be about (obligatory alms called) zakat.

The question to be asked at the fourth station will be about fasting.

The question to be asked at the fifth station will be about pilgrimage (the hajj).

The question to be asked at the sixth station will be about the rights of humans, the rights of parents, and whether one took care of one's relatives.

The question to be asked at seventh station will be about whether one performed ghusl (ritual bath) or not.

Of them, whichever is found wanting, one will burn in Hell as much as it requires. However, one will pass easily the station that will be found satisfactory. The following hadith-i sharifs declare:

(People will cross the bridge that will be over Hell. On the bridge will be thorny iron, hooks, and clasps, which will catch people from the right and left. The angels on the bridge will pray, "O my Allah, give salvation." Some will cross the bridge like lightning; some, like the wind; some, like a running horse; some, by running; some, by walking; some, by crawling; some, by creeping. As for those who will go to Hell, they will neither die nor attain a new life. After sinners burn in Hell as much as their sins, intercession for them [sinners] will be permitted.) [Bukhari]

(The Sirat is thinner than a hair and sharper than a sword. Angels will try hard to save Believers. Jabrail 'alaihis-salam will grip my waist, and I will pray, "O my Lord! Give salvation to my nation and rescue them." On that day many people who will slip and fall.) [Bayhaqi]

(When a person who is obedient to Allahu ta'ala and who pays the right of his property comes to the Sirat on the Day of Resurrection, his property will say to him, "Pass over it because you paid Allah's right on me." Afterwards, a person who did not pay Allah's right on his property will come, and his property will say to him, "Why did you not pay Allah's right on me? He will mutter to himself, "Woe is me. What did I do?") [Bayhaqi]

(Whoever wants not to be kept waiting at Sirat as much as a blink of an eye, let him not say anything about Allah's religion out of his own opinion.) [Qurtubi]

When Believers cross the Sirat, they will come across two springs. They will have a bath from one of the springs and will drink from the other. Thus, after attaining material and spiritual purity, they will come to the gate of Paradise. Angels will say, as it is stated in Zumar Sura, "Peace be upon you. Welcome! Enter here eternally." Then they will be clothed garments of Paradise, and all of them will go into Paradise.