Narrated Anas: The Prophet ﷺ used to make supplication for rain in this manner. he spread his hands keeping the inner side (of hands) towards the earth, so I witnessed the whiteness of his armpits.
The hadith also teaches us about the importance of prayer in Islam; it is not only done during times of hardship or need but can also be used to ask Allah for blessings such as rain which are essential for life on Earth. We should always remember that all our needs can be fulfilled through prayer if we turn towards Allah with sincere hearts and humble ourselves before Him.