Full Sharh — Riyad as-Salihin 809
وعن أبي الفضل العباس بن عبد المطلب رضي الله عنه قال: قلت يا رسول الله: علمني شيئًا أسأله الله تعالى، قال: "سلوا الله العافية" فمكثت أيامًا، ثم جئت فقلت: يا رسول الله: علمني شيئًا أسأله الله تعالى، قال لي: "يا عباس يا عم رسول الله سلوا الله العافية في الدنيا والآخرة". ((رواه الترمذي وقال: حديث حسن صحيح)).
English Translation
Abul-Fadl Al-`Abbas bin `Abdul-Muttalib (ra) reported:: I asked the Messenger of Allah (ﷺ) to teach me a supplication. He (ﷺ) said, "Beg Allah for safety (from all evils in this world and in the Hereafter)." I waited for some days and then I went to him again and asked him: "O Messenger of Allah Teach me to supplicate something from Allah." He said to me, "O Al-`Abbas, the uncle of Messenger of Allah! Beseech Allah to give you safety (Al-`afiyah ) in this life and in the Hereafter.".
Source
Riyad as-Salihin(رياض الصالحين)
The Book of Du'a (Supplications)
Hadith Number
809