Messenger of ALLAH peace and blessings of ALLAH be upon him) said:

Messenger of ALLAH peace and blessings of ALLAH be upon him) said:

“Deeds are shown (to ALLAH) on Mondays and Thursdays, and I like my deeds to be shown when I am fasting.”

Fasting is something which is just for ALLAH, and ALLAH will give multiple rewards without measure for it. The hadith says:

“[ALLAH says:] Fasting is Mine and it is I Who give reward for it.”

(Al-Bukhaari, Fath, no. 1904)

“There is nothing equivalent to fasting.”

(Al-Nisaa’i, 4/165; see also Saheeh al-Targheeb, 1/413)

“The prayer (du’aa’) of the fasting person will not be refused.”

(Reported by al-Bayhaqi, 3/345; see also al-Silsilah al-Saheehah, 1797)

“The one who fasts has two joys: the joy of breaking his fast and, when he meets his Lord, the joy of having fasted.”

(Reported by Muslim, 2/807)
Fasting will be an intercession for the slave on the Day of Resurrection, when it will say:

“O Lord, I stopped him from eating and drinking during the day, so let me intercede for him.”

(Reported by Ahmad, 2/174; al-Bayhaqi classed its isnaad as hasan in al-Mujtama’, 3/181; see also Saheeh al-Targheeb, 1/411).

“The smell (coming from the mouth of) the fasting person is better in the sight of ALLAH than the scent of musk.”

(Muslim, 2/808).

“Fasting is a protection and a strong fortress against the Fire.”

(Reported by Ahmad, 2/402; see also Saheeh al-Targheeb, 1/411 and Saheeh al-Jaami’, 3880)

“Whoever fasts one day for the sake of ALLAH, ALLAH will keep his face seventy years’ distance away from the Fire because of it.”

(Reported by Muslim, 2/808)

“Whoever fasts a day seeking the pleasure of ALLAH and then dies [i.e. that is the last thing he does] will enter Paradise.”

(Reported by Ahmad, 5/391; see also Saheeh al-Targheeb, 1/412)

“In Paradise there is a gate called al-Rayyaan, through which those who fast will enter, and no-one else will enter through it. After they have entered, it will be locked and no-one else will enter it.”

(Al-Bukhaari, Fath, no. 1797).

FASTING on MONDAYS and THURSDAYS:
It was narrated from Abu Qataadah al-Ansaari that the Messenger of ALLAH (salAllahu ‘alayhi wa sallam) was asked about fasting on Mondays. He said:

“On that day I was born, and on it the Revelation came to me.”

Narrated by Muslim, 1162.
It was narrated that ‘Aa’ishah (r.a) (may ALLAH be pleased with her) said: The Prophet (salAllahu ‘alayhi wa sallam) was keen to fast on Mondays and Thursdays.
Narrated by al-Tirmidhi, 745; al-Nasaa’i, 2361; Ibn Maajah, 1739; classed as saheeh by al-Albaani in Saheeh al-Targheeb, 1044.
It was narrated from Abu Hurayrah (may ALLAH be pleased with him) that the Messenger of ALLAH (peace and blessings of ALLAH be upon him) said:

“Deeds are shown (to ALLAH) on Mondays and Thursdays, and I like my deeds to be shown when I am fasting.”

Narrated by al-Tirmidhi, 747; classed as saheeh by al-Albaani in Saheeh al-Targheeb, 1041.

Observing Sawm on Monday and Thursday is permissible. It is related by Abu Dawud on the authority of Usamah ibn Zayd (may ALLAH be pleased with both of them) that the Prophet (peace be upon him) replied to the question of why he always observed Sawm on Monday and Thursday saying: The works of the people are presented (to ALLAH) on Monday and Thursday. In another narration: I would like my deeds to be shown (to ALLAH) while I am fasting. This Hadith clearly indicates that observing Sawm on Monday and Thursday is permissible and is a Sunnah (supererogatory act of worship following the example of the Prophet 'Sallallahu Alayhi Wa Sallam').).

May ALLAH grant us success! May peace and blessings be upon our Prophet Muhammad 'Sallallahu Alayhi Wa Sallam' his family and Companions!
A'ameen Ya Aalamin!