Narrated Al-Miswar bin Makhrama:
When 'Umar was stabbed, he showed signs of agony. Ibn 'Abbas, as if intending to encourage 'Umar, said to him, "O Chief of the believers! Never mind what has happened to you, for you...
O Allah, Lord of the seven heavens, Lord of the Magnificent Throne, be for me a support against [such and such a person] and his helpers from among your creatures, lest any of them abuse me or do me wrong. Mighty is...
-> Read More Info: Al-Bukhari, Al-'Adab Al-Mufrad (no. 707). Al-Albani graded it authentic in Sahih Al-'Adab Al-Mufrad (no. 545).