The Messenger of Allah ﷺ said: Pray two rak'ahs before the Maghrib prayer. He then said (again): Pray two rak'ahs before the Maghrib prayer, it applies to those who wish to do so. That was because he feared that the people might treat it as sunnah.  

قَالَ رَسُولُ اللَّهِ ﷺ صَلُّوا قَبْلَ الْمَغْرِبِ رَكْعَتَيْنِ ثُمَّ قَالَ صَلُّوا قَبْلَ الْمَغْرِبِ رَكْعَتَيْنِ لِمَنْ شَاءَ خَشْيَةَ أَنْ يَتَّخِذَهَا النَّاسُ سُنَّةً  

I offered two rak'ahs of prayer before the Maghrib prayer (i.e. obligatory) during the time of the Messenger of Allah ﷺ. I (narrator al-Mukhtar b. Fulful) asked Anas: Did the Messenger of Allah ﷺ se you ? He replied: Yes, but he neither commanded us nor forbade us (to do so).  

صَلَّيْتُ الرَّكْعَتَيْنِ قَبْلَ الْمَغْرِبِ عَلَى عَهْدِ رَسُولِ اللَّهِ ﷺ قَالَ قُلْتُ لأَنَسٍ أَرَآكُمْ رَسُولُ اللَّهِ ﷺ قَالَ نَعَمْ رَآنَا فَلَمْ يَأْمُرْنَا وَلَمْ يَنْهَنَا  

The Messenger of Allah ﷺ as saying: Between the two adhans there is a prayer, between the two adhans there is prayer for one who desires (to offer).  

قَالَ رَسُولُ اللَّهِ ﷺ بَيْنَ كُلِّ أَذَانَيْنِ صَلاَةٌ بَيْنَ كُلِّ أَذَانَيْنِ صَلاَةٌ لِمَنْ شَاءَ  

Ibn 'Umar was asked about praying two rak'ahs before the Maghrib prayer. He replied: I did not see anyone praying them during the time of the Messenger of Allah ﷺ. He (Ibn Umar) permitted to pray two rak'ahs after the Asr prayer. Abu Dawud said: I heard Yahya b. Ma'in say: The correct name of the narrator Abu Shu'aib is the Shu'aib. Shu'bah made a mistake in narrating his name.  

مَا رَأَيْتُ أَحَدًا عَلَى عَهْدِ رَسُولِ اللَّهِ ﷺ يُصَلِّيهِمَا وَرَخَّصَ فِي الرَّكْعَتَيْنِ بَعْدَ الْعَصْرِ