Is fasting in the month of Rajab an innovation (bid'ah), and is performing Umrah in it permissible, and does it have any other special characteristics?

Scholars have differed regarding fasting in the month of Rajab. The majority of scholars are of the opinion that it is recommended, and they have cited evidence from hadiths, including the hadith of Abu Mujibah al-Bahili and the hadith of Usamah ibn Zayd. Al-Shawkani held that the hadith of Usamah indicates the recommendation of fasting in Rajab.

Conversely, some scholars, such as the Hanbalis, disliked singling out Rajab for fasting, and they cited as evidence the hadith of Ibn Abbas and the prohibition by Umar. However, the dislike among the Hanbalis is removed by fasting even one day from Rajab or by fasting in another month. The preponderant opinion is that of the majority of scholars.

As for performing 'Umrah in Rajab, there is no established report of the Prophet (peace be upon him) having performed it, though some of the Salaf deemed it recommended. It is obligatory to avoid innovations prevalent in Rajab, such as Salat al-Ragha'ib.