A woman asked Allah's Messenger (ﷺ), "O Allah's Messenger (ﷺ)! What should we do, if the blood of menses falls on our clothes?" Allah's Messenger (ﷺ) replied, "If the blood of menses falls on the garment of anyone of you, she must take hold of the blood spot, rub it, and wash it with water and then pray in (with it).
Sahih al-Bukhari Book 6, Hadith 12
← Previous Hadith Fatima bint Abi Hubaish said to Allah's Messenger (ﷺ), "O Allah's Messenger (ﷺ)! I do not become clean (from bleeding). Shall I give up my prayers?" Allah's Messenger (ﷺ) replied: "No, because it is from a blood vessel and not the menses. So when the real menses begins give up your prayers and when it (the period) has finished wash the blood off your body (take a bath) and offer your prayers."

Sahih al-Bukhari Book 6, Hadith 11 Next Hadith → Whenever anyone of us got her menses, she, on becoming clean, used to take hold of the blood spot and rub the blood off her garment, and pour water over it and wash that portion thoroughly and sprinkle water over the rest of the garment. After that she would pray in (with) it.

Sahih al-Bukhari Book 6, Hadith 13