Narrated Anas bin Malik: The Messenger of Allah ﷺ fixed forty days to shave the pubes, paring the nails, clipping the moustaches, and plucking the hair under the armpit. Abu Dawud said: Jafar bin Sulaiman transmitted it from Abu Imran on the authority of Anas. In this version he did not mention the Prophet ﷺ. He said: Forty days were fixed for us. This is a more correct version.
Hadith Referenceسنن ابي داود / كتاب الترجل / 4200
Hadith Gradingالألبانی:صحيح | زبیر علی زئی:ضعيف, إسناده ضعيف, ترمذي (2758), صدقة بن موسي الدقيقي : ضعيف و قال الھيثمي : ضعفه الجمھور (مجمع الزوائد 286/5) وحديث مسلم (258) يغني عنه, انوار الصحيفه، صفحه نمبر 149
Benefits and Issues: This narration is weak in its chain of transmission; however, regarding the period of forty days, there is a narration present in Sahih Muslim. See: (Sahih Muslim, Book of Purification, Chapter: Characteristics of Fitrah, Hadith: 658). In addition, Shaykh al-Albani rahimahullah has also declared this narration to be authentic. See: (Sahih Abu Dawud, the mentioned book). Therefore, it is understood that the period of forty days is the maximum limit. It is not permissible to exceed this.
Source: Sunan Abu Dawood – Commentary by Shaykh Umar Farooq Saeedi, Page: 4200