Abu Dawud said: In the version of both the narrators the words are "he will be required to work and must not be overburdened". This is the version of 'Ali.
In-book : Book 31, Hadith 13
English translation : Book 30, Hadith 3927
31. The Book of Manumission of Slaves
باب مَنْ ذَكَرَ السِّعَايَةَ فِي هَذَا الْحَدِيثِ