All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.
The two Rak‘ahs before the Maghrib prayer are recommended and not a Sunnah Raatibah (not a regular action of the Sunnah).
Ibn Al-Qayyim said in Zaad Al-Ma’aad:
“As for the two Rak‘ahs before the Maghrib, it was not reported that the Prophet used to pray them; but it was authentically reported that he approved his Companions doing so, as he saw them praying it, and he neither forbade them nor ordered them to do it.
‘Abdullah Al-Muzani, may Allah be pleased with him, narrated that the Prophet said, 'Pray two Rak‘ahs before the Maghrib prayer; pray two Rak‘ahs before the Maghrib prayer.' He then said it the third time and added, 'For those who wish to do it,' fearing that the people might take it as a Sunnah. [Al-Bukhaari and Muslim] This is the correct view about these two Rak‘ahs, that they are recommended but are not a regular action of the Sunnah.”
It is also recommended to pray two Rak‘ahs before the ‘Ishaa' prayer; An-Nawawi said in Al-Majmoo’, “It is recommended to pray two Rak‘ahs or more before the ‘Ishaa' prayer. ‘Abdullah ibn Mughaffal, may Allah be pleased with him, narrated that the Prophet said, 'Between every two athaans (i.e. the athaan and the Iqaamah) there is a prayer, between every two athaans there is a prayer; between every two athaans, there is a prayer,' and after saying it for the third time, he said, 'For whoever wants to.' [Al-Bukhaari and Muslim]”
It is recommended for a Muslim to persist in doing the supererogatory acts of worship in general and not stop them after being persistent in doing them.
Ibn Hajar said in Fat-h Al-Baari, “It is recommended to persist in doing the goodness that a person was used to do without any negligence; this indicates that it is disliked to stop performing an act of worship even if it is not obligatory.”
Allah knows best.