The Messenger of Allah ﷺ used to offer the Zuhr prayer in midday heat; and no prayer was harder on the Companions of the Messenger of Allah ﷺ that this one. Hence the revelation came down: "Be guardians of your prayers, and of the midmost prayer" (2:238). He (the narrator) said: There are two prayers before it and two prayers after it. (Using translation from Abū Dāʾūd 411)
كَانَ رَسُولُ اللهِ ﷺ يُصَلِّي الظُّهْرَ بِالْهَاجِرَةِ وَلَمْ يَكُنْ يُصَلِّي صَلَاةً أَشَدَّ عَلَى أَصْحَابِ النَّبِيِّ ﷺ مِنْهَا قَالَ فَنَزَلَتْ {حَافِظُوا عَلَى الصَّلَوَاتِ وَالصَّلَاةِ الْوُسْطَى} [البقرة 238] قَالَ إِنَّ قَبْلَهَا صَلَاتَيْنِ وَبَعْدَهَا صَلَاتَيْنِ