Answer
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
Salat Al-Raghaib is one of the innovations (bidahs) that have been introduced in the month of Rajab. It is done on the night of the first Friday in Rajab, between Maghrib and Isha, and is preceded by fasting on the first Thursday of Rajab.
Answering your question, the Fatwa Center at Islam Q and A, states:
Origin of Salat Al-Raghaib
Salat Al-Raghaib was first introduced in Bayt al-Maqdis (Jerusalem) in 480 AH. There is no report that the Prophet (peace be upon him) did it, or any of his companions, or any of the best generations or imams. This alone is sufficient to prove that it is a reprehensible innovation, and it is not a praiseworthy Sunnah.
Is Salat Al-Raghaib Recommended?
The scholars have warned against it and pointed out that it is innovation and misguidance.
An-Nawawi (may Allah have mercy on him) said in al-Majmu (3/548)
“The prayer which is known as Salat Al-Raghaib, which is twelve rakahs that are offered between Maghrib and Isha on the night of the first Friday in Rajab, and praying one hundred rakahs on the night of Shaban 15th are both reprehensible innovations. No one should be deceived by the fact that they are mentioned in Qut al-Qulub and Ihya Ulum al-Deen, or by the hadith which is quoted in these two books, because all of that is false. No one should be deceived by some of those imams who were confused about the ruling on these prayers and wrote essays stating that they are recommended, for they are mistaken in that. Imam Abu Muhammad Abd al-Rahman ibn Ismail al-Maqdisi wrote a valuable book showing that they are false, and he did well in that, may Allah have mercy on him.”
Ibn Aabideen said in his Hashiyah (2/26):
“It says in Al-Bahr: Hence we know that it is makruh to gather for Salat Al-Raghaib, which is done on the first Friday of Rajab, and that it is an innovation.
The scholar Nur al-Din al-Maqdisi wrote a good essay on this topic which he called Rad` al-Raghib an Salat Al-Raghaib , in which he covered most of the comments of earlier and later scholars among the four madhhabs.”
Ibn Hajr Al-Haytami (may Allah have mercy on him) was asked: Is it permissible to offer Salat Al-Raghaib in congregation or not?
He replied:
“Salat Al-Raghaib is like the prayer that is known as laylat al-nisf min Shaban (half way through Shaban). These are two reprehensible innovations and the hadith which speaks of them is mawdu (fabricated). It is forbidden to offer these prayers either individually or in congregation.”
Almighty Allah knows best.
Source: wwwislamqa.info