Praise be to Allah.
The hadeeth applies to both the father and the mother. The Prophet (peace and blessings of Allaah be upon him) also said, “Whoever has two daughters and treats them kindly, they will be a protection for him against the Fire.” The same applies if he has sisters or paternal or maternal aunts etc., and he treats them kindly, we hope that he will attain Paradise for that. For when he treats them kindly, he deserves a great reward and to be protected from the Fire, so he will be kept away from the Fire because of his good deed.
This applies only to Muslims, because if a Muslim does these good deeds seeking the pleasure of Allaah, he will have earned salvation from the Fire. There are many means of gaining salvation from the Fire and admittance to Paradise, so the believer should try to attain many of them. Islam itself is the only means and is the basic cause of gaining admittance to Paradise and salvation from the Fire.
There are actions which, if the Muslim does them, he will enter Paradise and be saved from Hell, such as taking care of daughters or sisters, then they will be a protection for him against the Fire. Whoever dies leaving behind three little ones who have not yet reached the age of puberty, they will be a protection for him against the Fire. They said, “O Messenger of Allaah, what about two?” He said, “And two.” They did not ask him about one. It was narrated in a saheeh (authentic) report that he (peace and blessings of Allaah be upon him) said: “Allaah says, if I take from My slave the one whom he loves most in this world and he bears that with patience seeking reward from Me, he will have no less a reward than Paradise.” So Allaah explains that the believing slave has no less a reward with Him than Paradise, if He takes one whom he loves of the people of this world, and he bears that with patience and seeks reward. One of our little ones is included in this hadeeth, if Allaah takes him and causes him to die, and his father or mother or both bear that with patience and seek reward, then they will have Paradise. This is a great bounty from Allaah. The same applies to husbands, wives and all other relatives and friends, if they are patient and seek reward then they are included in this hadeeth, so long as they take care to avoid anything which could prevent that, such as dying committing major sin. We ask Allaah to keep us safe and sound.