The Prophet ﷺ went towards the Musalla and invoked Allah for rain. He faced the Qibla and wore his cloak inside out, and offered two rakʿat.
أَنَّ النَّبِيَّ ﷺ خَرَجَ إِلَى الْمُصَلَّى فَاسْتَسْقَى فَاسْتَقْبَلَ الْقِبْلَةَ وَقَلَبَ رِدَاءَهُ وَصَلَّى رَكْعَتَيْنِ قَالَ أَبُو عَبْدِ اللَّهِ كَانَ ابْنُ عُيَيْنَةَ يَقُولُ هُوَ صَاحِبُ الأَذَانِ وَلَكِنَّهُ وَهْمٌ لأَنَّ هَذَا عَبْدُ اللَّهِ بْنُ زَيْدِ بْنِ عَاصِمٍ الْمَازِنِيُّ مَازِنُ الأَنْصَارِ
"Sufyan said: 'I asked 'Abdullah bin Abi Bakr who said: I heard it from Abbad bin Tamim who narrated it from his father, that 'Abdullah bin Zaid, who was shown the call to prayer (in a dream) said: 'The Messenger of Allah ﷺ went out to the prayer place to pray for rain. He faced the kiblah and turned his cloak around and prayed two rak'ahs.'"
إِنَّ رَسُولَ اللَّهِ ﷺ خَرَجَ إِلَى الْمُصَلَّى يَسْتَسْقِي فَاسْتَقْبَلَ الْقِبْلَةَ وَقَلَبَ رِدَاءَهُ وَصَلَّى رَكْعَتَيْنِ قَالَ أَبُو عَبْدِ الرَّحْمَنِ هَذَا غَلَطٌ مِنِ ابْنِ عُيَيْنَةَ وَعَبْدُ اللَّهِ بْنُ زَيْدٍ الَّذِي أُرِيَ النِّدَاءَ هُوَ عَبْدُ اللَّهِ بْنُ زَيْدِ بْنِ عَبْدِ رَبِّهِ وَهَذَا عَبْدُ اللَّهِ بْنُ زَيْدِ بْنِ عَاصِمٍ