´Abdullah narrated:` "The Messenger of Allah would fasting during the beginning of every month for three days, and Friday was the least of the days that he did not fast."
Hadith Referenceسنن ترمذي / كتاب الصيام عن رسول الله صلى الله عليه وسلم / 742
Hadith Gradingالألبانی:حسن تخريج المشكاة (2058) ، التعليق على ابن خزيمة (2149) ، صحيح أبي داود (2116) | زبیر علی زئی:(746) إسناده ضعيف, خيثمة بن عبدالرحمن كم يسمع من عائشه رضي الله عنها (د 2128)
Narrated Abdullah ibn Masud: The Messenger of Allah ﷺ used to fast three days every month.
Shaykh Umar Farooq Saeedi
Benefits and Issues: The virtue of the white days (Ayyam al-Beed) is established. And the Prophet sallallahu alayhi wa sallam would sometimes fast three days without specifying or designating particular days, so that it would not be understood as obligatory. In this way, sometimes he would fast three days at the beginning of the month. The days that came to the knowledge of Abdullah ibn Mas'ud radi Allahu anhu were these initial days, so he reported accordingly. And the days that came to the knowledge of Aisha radi Allahu anha were the fasts of the white days (Ayyam al-Beed), which he would often observe, so Aisha radi Allahu anha reported accordingly. Therefore, there is no contradiction between the two.
Source: Sunan Abu Dawood – Commentary by Shaykh Umar Farooq Saeedi, Page: 2450
´It was narrated that 'Abdullah bin Masud said:` "The Messenger of Allah used to fast three days in the middle of every month, and he rarely did not fast on Friday."
Hafiz Muhammad Ameen
(1) "From the beginning" means in any month. And sometimes he would fast three days from the middle, and sometimes he would also fast from the end of the month.
(2) "On the day of Jumu‘ah (Friday)." That is, including Thursday; otherwise, he (sallallahu alayhi wa sallam) forbade fasting on Friday alone. See: (Sahih al-Bukhari, al-Sawm, Hadith: 1985, and Sahih Muslim, al-Siyam, Hadith: 1144). Fasting on Thursday was his regular practice.
Source: Sunan Nasa'i: Translation and Benefits by Shaykh Hafiz Muhammad Amin Hafizullah, Page: 2370