Hadith: Wash her three times, or five times, or more if you find that necessary. Wash her with water and Sidr (ground lote leaves), add camphor—or a pinch of camphor—to water in the last time, and let me know when you finish

عَنْ أُمِّ عَطِيَّةَ رَضيَ اللهُ عنها قَالَتْ:
تُوُفِّيَتْ إِحْدَى بَنَاتِ النَّبِيِّ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ، فَخَرَجَ النَّبِيُّ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ فَقَالَ: «اغْسِلْنَهَا ثَلاَثًا، أَوْ خَمْسًا أَوْ أَكْثَرَ مِنْ ذَلِكَ، إِنْ رَأَيْتُنَّ بِمَاءٍ وَسِدْرٍ، وَاجْعَلْنَ فِي الآخِرَةِ كَافُورًا -أَوْ شَيْئًا مِنْ كَافُورٍ-، فَإِذَا فَرَغْتُنَّ فَآذِنَّنِي»، قَالَتْ: فَلَمَّا فَرَغْنَا آذَنَّاهُ، فَأَلْقَى إِلَيْنَا حِقْوَهُ، فَقَالَ: «أَشْعِرْنَهَا إِيَّاهُ»، وَقَالَتْ: وَجَعَلْنَا رَأْسَهَا ثَلاَثَةَ قُرُونٍ.
[صحيح] - [متفق عليه] - [صحيح البخاري: 1258]

’Umm ‘Atiyyah (may Allah be pleased with her) reported:
One of the daughters of the Prophet (ﷺ) passed away, so the Prophet (ﷺ) went out and said: "Wash her three times, or five times, or more if you find that necessary. Wash her with water and Sidr (ground lote leaves), add camphor—or a pinch of camphor—to water in the last time, and let me know when you finish." She said: When we finished, we told him, so he gave us his lower garment and said: "Let it be the first thing you shroud her in." She said: We plaited her hair into three braids.
[Authentic] - [Agreed upon] - [Sahīh Al-Bukhāri - 1258]

Explanation

Zaynab, the daughter of the Prophet (ﷺ), passed away. The Prophet (ﷺ) entered upon the women who were to wash her and said to them: Wash her with water and lote leaves an odd number of times—three, or five, or more if needed—and in the final wash, add some camphor. When you finish, inform me. When they finished washing her, they informed him. He then gave his lower garment to the women who washed her and said: Wrap her in it, and make it the garment closest to her body. Then her hair was braided into three plaits.

Benefits from the Hadith

1. The washing of a deceased Muslim is obligatory, and it is a communal duty.
2. A woman is only to be washed by women, and a man only by men—except in the cases of a wife with her husband and a female slave with her master, for each of them may wash the other.
3. The washing should be done three times; if that is not sufficient, then five times; and if still not sufficient, more may be added as needed, according to what is beneficial and necessary. Afterward, if any impurities come out of the body, the place from which the filth exits should be sealed.
4. The one performing the washing should make the number of washings odd—three, five, or seven.
5. As-Sindi said: This Hadīth indicates that there is no fixed number of washings for the deceased; rather, what is required is cleanliness, but the odd number should be observed.
6. Lote leaves should be used with the water, because they cleanse and firm up the body of the deceased.
7. The deceased should be perfumed during the final washing, so that the scent is not washed away by water. The perfume should be camphor, because—in addition to its pleasant fragrance—it firms up the body and helps prevent it from decaying quickly.
8. The washing should begin with the honored parts of the body, namely, the right sides and the body parts required in ablution.
9. It is recommended to comb the hair of a deceased woman, braid it into three plaits, and place them behind her.
10. It is permissible to cooperate in washing the deceased, but none should be present except those who are needed.
11. Seeking blessings through the belongings of the Prophet (ﷺ), such as his clothing, is permissible—but this is something unique to him and does not extend to other scholars or righteous people, because such matters are based on religious texts. The Companions never practiced this with anyone other than him, for doing so with others would lead to Shirk (polytheism) and be a source of trial for the one whom people seek blessing through.
12. It is permissible to delegate a trustworthy person to carry out a task he has been entrusted with, provided he is qualified for such delegation.