Bukhari

Hadith Commentary:
The reason for the naming of Sha'ban, in the words of Hafiz Sahib, is: "l-tashaʿubihim fi talab al-miyah aw fi al-gharat baʿda an yakhruj shahr Rajab al-haram" (Fath).
That is, the Arabs used to disperse in search of water during this month, or after the conclusion of the month of Rajab, in which the Arabs would completely refrain from killing, fighting, etc., in this month they would again seek such opportunities.
For this reason, they named this month Sha'ban.

Hadith Commentary:

Benefits and Issues:
Regarding voluntary fasts (nafl), the Messenger of Allah (sallallahu alayhi wa sallam) did not have any fixed or rigid routine or practice. Rather, sometimes he (sallallahu alayhi wa sallam) would begin to fast continuously without interruption, and at other times he would leave gaps in his continuous fasting. Sometimes he would fast on Saturday, Sunday, and Monday at the beginning of a month, and in the next month he would fast on Tuesday, Wednesday, and Thursday. Every week, he would fast on Monday and Thursday.

The purpose of this was that there should not be any hardship or difficulty in keeping voluntary fasts, but rather the way of ease should remain open, so that every person may fast according to his own circumstances, conditions, and ability.

The Prophet (sallallahu alayhi wa sallam) used to keep the most voluntary fasts in the month of Sha’ban, because in this month the deeds of the servants are presented before Allah, and he (sallallahu alayhi wa sallam) wished that when his deeds were presented, he should be in a state of fasting.

However, there was no month, in fact, not even a week, in which he (sallallahu alayhi wa sallam) was free from fasting.

1:
The reason for this was so that no one would assume its obligation.

(1) There is no set regulation for voluntary fasts (nafl), rather, it depends on a person’s enthusiasm: whenever one wishes, one may fast, and as many as one wishes; and whenever one feels lethargic, one may refrain from fasting, and may leave off fasting for as long as one wishes. (See also, Hadith: 2359)

(2) The reason for observing more fasts in Sha’ban could be the nearness of the blessed month of Ramadan; thus, due to being the neighbor of Ramadan, Sha’ban also attains a special virtue. The proximity of the Prophets and the righteous (anbiya wa salihin) is also a great cause of virtue, whether in this world, the Hereafter, or in the grave.

(3) “The entire Sha’ban”—for its details, see: (Hadith: 2177)

Urdu marginal note:
"After arriving in Madinah Munawwarah"—because it is only regarding the period after this that Hafsah radi Allahu anha has knowledge; otherwise, it does not mean that before coming to Madinah Munawwarah the Prophet sallallahu alayhi wa sallam used to fast continuously. Rather, even before, this was his blessed habit.

Commentary: ➊
It is also permissible to keep voluntary (nafl) fasts consecutively, provided that each fast is broken (i.e., iftar is done) every day, meaning that continuous fasting without breaking (wisal) is not allowed for us, because that is prohibited for us. See (Sahih al-Bukhari, Book of Fasting, Chapter on Wisal, Hadith 1961 and Sahih Muslim, Book of Fasting, Chapter on the Prohibition of Wisal, Hadith 1102).
➋
Voluntary fasts can be observed in every month of the year.
➌
To keep voluntary fasts for an entire month consecutively is contrary to the Sunnah.
➍
In the month of Sha'ban, there should be greater emphasis on observing voluntary fasts.

Takhrij al-Hadith:
[وأخرجه البخاري 1969، ومسلم 175/1156، من حديث مالك به]

Jurisprudential Explanation:
➊ Besides Ramadan, it is also Sunnah and a highly meritorious act to observe many fasts in other months as well.
➋ Sayyiduna Ibn Abbas radi Allahu anhu said: Whoever has missed fasts of Ramadan and another Ramadan arrives, then (after Ramadan) he must make up each missed fast (qada) and, for each missed fast, feed a poor person as well. [السنن الكبريٰ للبيهقي 253/4 و سنده قوي، رواية شعبه عن المدلسين محمولة على السماع]
◄ Sayyiduna Abu Hurairah radi Allahu anhu said: Whoever is present in (the month of) Ramadan should fast during it, and (later) make up the missed fasts, and for each missed fast, feed a poor person. [سنن الدارقطني 2/197 ح2321 وسنده حسن وقال الدارقطني : ”إسناد صحيح“، السنن الكبريٰ للبيهقي 4/253]
➌ Qasim bin Muhammad bin Abi Bakr rahimahullah said: Whoever has remaining make-up fasts (qada) of Ramadan, and despite having the ability to fast, does not make them up until the next Ramadan arrives, then for each missed fast, he must feed a poor person and also make up the fast. [الموطأ 1/308 ح691 ملخصاً وسنده صحيح]
➍ If one is unable to maintain consistency in some voluntary and meritorious acts, it is permissible; however, it is best to perform these acts with steadfastness.