Sa'id bin Sa'd bin 'Ubadah (RAA) narrated, 'A small weak man was staying in our tribe, and he committed adultery with one of their slave-women. Sa'd mentioned this to the Messenger of Allah (ﷺ), and thereupon he said, "Flog him (according to) the prescribed penalty." The people then said, 'O Messenger of Allah! He is too weak to bear it.' The Messenger of Allah (ﷺ) then said, "Get a stalk of the raceme of a palm tree with a hundred twigs and strike him just once." So, they did. Related by Ahmad, An-Nasa'i and Ibn Majah with a good chain of narrators.
English reference: Book 10, Hadith 1254
Arabic reference: Book 10, Hadith 1215