In this ayah, Allah is commanding the believers to protect themselves and their families from the Fire of Jahannam.
يَـٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوا۟ قُوٓا۟ أَنفُسَكُمْ وَأَهْلِيكُمْ نَارًا وَقُودُهَا ٱلنَّاسُ وَٱلْحِجَارَةُ عَلَيْهَا مَلَـٰٓئِكَةٌ غِلَاظٌ شِدَادٌ لَّا يَعْصُونَ ٱللَّـهَ مَآ أَمَرَهُمْ وَيَفْعَلُونَ مَا يُؤْمَرُونَ
O you who have believed, protect yourselves and your families from a Fire whose fuel is people and stones, over which are [appointed] angels, harsh and severe; they do not disobey Allah in what He commands them but do what they are commanded. (al-Tahrim: 6)
Protect yourself by doing what you’re commanded to do, and stay away from all that Allah and His Messenger have prohibited. And in addition to protecting ourselves, we need to look out for our families and try to protect them as well, by enjoining what is good and forbidding all those deeds that bring about Allah’s wrath and warrants punishment in the Hereafter. So teach them, warn them and guide them, in a way that is gentle, with patience and compassion. This includes your spouse, your children, your parents, siblings, and the closest family members that you live with.
And the fire of Jahannam has no comparison to the fire of the Dunya. It is extremely hot and it will be guarded by angels who will be harsh in manner, terrifying in their rebuke and frightening in their image.
In the Dunya, we have heard stories of corrupt prison guards, who accept bribes and allow things in and out of prisons, and in some instances even allowing inmates to escape. But no chance of that happening in the Hereafter, because the guards of Jahannam are not like that. They are stern, harsh, and will not afford any mercy to the occupants of the Hellfire, because they will be following the commands of their Lord. So no one can offer any bribes in exchange for release and thus no one will be able to escape.
So actively save yourselves and your family from the Fire. In particular teach your children and guide them to the path of doing good, because each person is responsible for those under him.
The Prophet ﷺ said, “All of you are guardians and are responsible for your wards. The ruler is a guardian and the man is a guardian of his family; the woman is a guardian and is responsible for her husband’s house and his children; and so all of you are guardians and are responsible for your wards.” (al-Bukhari)
The Prophet ﷺ said, “Order the children to pray when they reach the age of seven and when they reach the age of ten, discipline them for (not performing) it.” [Abu Dawud]
So never feel safe and assume that you will never enter the Fire because of your Iman. Allah is addressing the believers in this ayah, because even the believers are at risk of entering the Fire if they don’t repent and stay away from sins. So adopt measures today that will save you and your family from the punishment tomorrow! May Allah protect us all from entering Jahannam!