Short answer
By age ten. The Prophet ﷺ told parents to separate their children's beds at ten, alongside the order to pray. Hanafi scholars apply it to brothers and sisters, to children of the same sex, and to a child sleeping with a parent. It means separate beds or bedding, not necessarily separate rooms.
From age ten, children are not to share a bed or a single cover, whether brother and sister or two of the same sex, and a child of that age should not sleep in the same bed as a parent. Following this is wajib on the guardian.
The four schools agree on this.
Explanation
The Prophet ﷺ said: command your children to pray at seven, discipline them for it at ten, and separate them in their beds. The command to separate comes at the same age as firmness about prayer, because by ten children are starting to change and modesty must be protected before puberty arrives. The four schools agree on the age.
What separating means:
- Each child has their own bed, or at least their own mattress and covers.
- Sharing a bedroom is fine when space is tight. Bunk beds or two single beds work well.
- Brothers and sisters ideally have separate rooms once they near puberty, if the home allows.
- A child of ten or more should not regularly sleep in the parents' bed.
Same-sex siblings: the Hanafi scholars explain the hadith as covering two brothers or two sisters too, not only a brother and sister, since sleeping under one cover at that age can lead to things that harm modesty. Many families find this easier than expected once each child has their own space.
Before ten: sharing is allowed, but it is good to start building habits of privacy earlier: knocking before entering, changing clothes privately, and covering the body in front of others. See knocking before entering and the awrah of a child.
For the rest of the hadith, see when children start praying.
The evidence
Quran, Surah An-Noor 24:58
يَٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوا۟ لِيَسْتَـْٔذِنكُمُ ٱلَّذِينَ مَلَكَتْ أَيْمَٰنُكُمْ وَٱلَّذِينَ لَمْ يَبْلُغُوا۟ ٱلْحُلُمَ مِنكُمْ ثَلَٰثَ مَرَّٰتٍۢ ۚ مِّن قَبْلِ صَلَوٰةِ ٱلْفَجْرِ وَحِينَ تَضَعُونَ ثِيَابَكُم مِّنَ ٱلظَّهِيرَةِ وَمِنۢ بَعْدِ صَلَوٰةِ ٱلْعِشَآءِ ۚ ثَلَٰثُ عَوْرَٰتٍۢ لَّكُمْ ۚ لَيْسَ عَلَيْكُمْ وَلَا عَلَيْهِمْ جُنَاحٌۢ بَعْدَهُنَّ ۚ طَوَّٰفُونَ عَلَيْكُم بَعْضُكُمْ عَلَىٰ بَعْضٍۢ ۚ كَذَٰلِكَ يُبَيِّنُ ٱللَّهُ لَكُمُ ٱلْءَايَٰتِ ۗ وَٱللَّهُ عَلِيمٌ حَكِيمٌۭ ﴿٥٨﴾
O you who have believed, let those whom your right hands possess and those who have not [yet] reached puberty among you ask permission of you [before entering] at three times: before the dawn prayer and when you put aside your clothing [for rest] at noon and after the night prayer. [These are] three times of privacy for you. There is no blame upon you nor upon them beyond these [periods], for they continually circulate among you - some of you, among others. Thus does Allah make clear to you the verses; and Allah is Knowing and Wise.
Privacy within the home is part of how Islam raises children.
Sunan Abi Dawud 495
Graded hasan sahih... وفرقوا بينهم في المضاجع ...
"And separate them in their beds."
Children are to sleep apart from age ten.
Where the ruling is recorded
- al-Durr al-Mukhtar, Kitab al-Hazr wal-Ibaha, section on looking and touching. Children of ten are separated in beds, including a boy from his mother or sister.
- Radd al-Muhtar (Ibn Abidin), Kitab al-Hazr wal-Ibaha, section on looking and touching. Explains that the separation includes two brothers or two sisters.
Checked by our team. For a more accurate answer to your own situation, consult a scholar. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.