It is narrated from Umm Salamah (may Allah be pleased with her) that she said: I asked, "O Messenger of Allah (ﷺ)! I braid my hair, should I undo them when performing ghusl (ritual bath) after impurity?" He (ﷺ) replied: "No (there is no need to undo them), it is sufficient for you to pour three handfuls of water over your head, then pour water over the rest of your body, and you will be purified."
Hadith Referenceمسند الإمام الشافعي / كتاب الطهارة / 106
Hadith Takhrijاخرجه مسلم: الحيض، باب حکم ضغائر المغتسلة (330)