Compiled by Imam Yahya ibn Sharaf al-Nawawi
وعنه قال: كنا نصلي على عهد رسول الله صلى الله عليه وسلم ركعتين بعد غروب الشمس قبل المغرب، فقيل: أكان رسول الله صلى الله عليه وسلم صلاها؟ قال: كان يرانا نصليهما فلم يأمرنا ولم ينهنا". ((رواه مسلم)).
In the lifetime of the Messenger of Allah (ﷺ), we used to perform two Rak'ah (optional prayer) after sunset before the Maghrib prayer. It was asked: "Did Messenger of Allah (ﷺ) perform them?" He replied: "He saw us performing it, but he neither ordered us to perform them nor did he forbid us from doing so."[Muslim].