The month of Ramadan held valuable by Almighty Allah and His Messenger (PBUH); it is the only month stated by name in the Qur'an, and wherein the Qur'an was revealed, Allah Almighty says: {The month of Ramadhan [is that] in which was revealed the Qur’an, a guidance for the people and clear proofs of guidance and criterion.} [Al-Baqarah: 185 ],

 It is the only month Allah made its fasting obligatory upon Muslims, so the Messenger paid special attention to it which made his companions feel it is different from other months. Therefore, the Prophet made it detestable to fast the last half of Sha`ban to feel the particularity of fasting in Ramadan

It was narrated from Abu Hurairah that the Messenger of Allah (ﷺ) said: (When it is the middle of Sha’ban, do not fast until Ramadan comes.), Grade: Sahih

It may seem paradox for the following: Abu Salama reported: I asked 'A'isha (Allah be pleased with her) about the fasting of the Messenger of Allah (ﷺ). She said: He used to observe fast (at times so continuously) that we said: He has fasted (never to break), and he did not observe fast till we said: He has given up perhaps never to fast, and I never saw him observing (voluntary fasts) more in any other month than that of Sha'ban. (lt appeared as if) he observed fast throughout the whole of Sha'ban except a few (days).

This paradox may be solved through the narration related by At-Tirmidhi on the authority of Abu-Hurairah that the Prophet (PBUH) said: (Do not proceed the month of Ramadan with fasting unless it falls on a day that one of you would have (normally) fasted).

This means that for a Muslim not having been accustomed to fasting throughout the year, he/she shall not fast during the last half of Sha`ban. However, for a Muslim accustomed to fasting Mondays and Thursdays or fasting generally, he/she may fast during the last half of Sha`ban.

This explanation makes prophetic contexts go in line without contradiction.

http://300035.dotdothktrade.tech/en/artical/3407693/340-Sunnah-detestability-fast-second-half-Sha`aban