[Machine] The Prophet ﷺ prayed two units before Maghrib prayer, then he said after the third unit, "For whoever wishes." He was concerned that people would consider it a Sunnah.
أَنَّ رَسُولَ اللَّهِ ﷺ صَلَّى قَبْلَ الْمَغْرِبِ رَكْعَتَيْنِ * ثُمَّ قَالَ عِنْدَ الثَّالِثَةِ «لِمَنْ شَاءَ» خَافَ أَنْ يَحْسِبَهَا النَّاسُ سُنَّةً
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. (Using translation from Abū Dāʾūd 1281)
أَنَّ رَسُولَ اللهِ ﷺ قَالَ صَلُّوا قَبْلَ الْمَغْرِبِ رَكْعَتَيْنِ ثُمَّ قَالَ صَلُّوا قَبْلَ الْمَغْرِبِ رَكْعَتَيْنِ ثُمَّ قَالَ عِنْدَ الثَّالِثَةِ لِمَنْ شَاءَ كَرَاهِيَةَ أَنْ يَتَّخِذَهَا النَّاسُ سُنَّةً