The Messenger of Allah ﷺ said, "Whoever prays six rakahs after the sunset prayer without speaking any evil between them, they will be counted for him as the worship of twelve years."
حدثنا أبو كريب يعني محمد بن العلاء الهمداني حدثنا زيد بن الحباب حدثنا عمر بن أبي خثعم عن يحيى بن أبي كثير عن أبي سلمة
قال رسول الله ﷺ من صلى بعد المغرب ست ركعات لم يتكلم فيما بينهن بسوء عدلن له بعبادة ثنتي عشرة سنة
[Its chain of transmission is extremely daif] Ibn Majah also narrated it in Iqamat al-Salawat, chapter on what has been said regarding the six rakats after Maghrib, hadith no. 1167, 1374, from the hadith of Zayd bin Hubab, with the same wording. The hadith, "Whoever prays twenty rakats after Maghrib..." and so on, is fabricated. Ibn Majah narrated it, hadith no. 1373.