Some reasons for the punishment in the grave are: shirk and kufr, hypocrisy, changing the religion of Allah, not taking care to avoid getting urine on oneself, spreading malicious gossip among people, ghibah, lying, forsaking the Quran after having learned it, sleeping and missing an obligatory prayer, consuming riba, zina, enjoining righteousness upon others and forgetting oneself, breaking the fast in Ramadan with no excuse, stealing from the war booty, dragging one’s garment out of pride, stealing from the pilgrims, detaining animals and tormenting them, and debt.

1- Punishment of the grave will be for many of the sinners among those who affirmed the Oneness of Allah, such as those who slept and (intentionally) missed obligatory prayers, or those who committed Zina, consumed Riba (usury/interest) and liars whose lies spread far and wide. 2- The squeezing of the grave will happen to everyone; even the righteous among the believers will experience some of that.

Here is how to treat non-Muslims: 1. Islam urges Muslims to show kindness to parents even if they are non-Muslims. 2. Islam advises Muslims to treat neighbors kindly even if they are not Muslim. 3. Islam encourages Muslims to ensure justice and show kindness to non-Muslims who are not fighting Muslims. 4. Islam prohibits killing non-Muslims living under Muslim rule. 5. Islam prohibits wronging a mu‘ahid, detracting from his rights, or burdening him with more work. 6. Islam prohibits committing transgression and commands justice.

There are three degrees of Islam, which are: Islam, iman and ihsan. Each of them has a meaning and certain pillars or essential parts which are explained in the detailed answer.

Praying to the occupant of the grave is major shirk. Praying the funeral prayer at the graveside is permissible. Praying the funeral prayer in the graveyard is permissible. Praying towards the graveyard is haram according to the correct opinion.

The greatest intercession is al-maqam al-mahmud, which the earlier and later generations will ask the Prophet to intercede for them with their Lord so that He might relieve them of the horrors of the Day of Judgement.

Tawhid al-Rububiyyah means affirming that Allah is One and Unique in His actions, such as creation, sovereignty, controlling affairs, provision, giving life and death, sending down the rain, and so on. A person’s Tawhid is not complete unless he affirms that Allah is the Lord, Sovereign, Creator and Provider of all things.

The conditions of accepting the shahadah are: knowledge, certainty, acceptance, submission, truthfulness, sincerity, and love.

The conditions of La ilaha illa-Allah are: knowledge, certainty, submission, following, truthfulness, sincerity and love.