Whenever they suffered drought, Umar bin Khattab would seek rain through Abbas bin Abdul-Muttalib, saying, "O Allah, we used to seek means to You through our Prophet and You would give us rain. Now we seek means to You through the uncle of our Prophet, so give us rain."And so they would be given rain.
أن عمر بن الخطاب كان إذا قحطوا استسقى بالعباس بن عبد المطلب فقال: اللهم إنا كنا نتوسل إليك بنبينا فتسقينا، وإنا نتوسل إليك بعم نبينا فاسقنا. قال: فيسقون.
Bukhari related it in the Book of Rain Prayer (1010), from Hasan bin Muhammad, who said, Muhammad bin Abdullah Ansari told us, who said, my father Abdullah bin Muthanna told me, from Thumama bin Abdullah bin Anas, from Anas, who said, then he mentioned it.