The Prophet ﷺ performed the prayer for rain, prayed two units, and turned his cloak inside out.
أخبرنا قتيبة عن سفيان عن عبد الله بن أبي بكر
أن النبي ﷺ استسقى وصلى ركعتين وقلب رداءه
[Sahih] Mentioned previously, no. 1506, and it is in Kubra, no. 1813.