"I sold him the sand."
Translation:Sprzedałem mu piasek.
'Sprzedałem mu piasek.' is the correct form. See: http://pokulture.pl/index.php?itemid=427&catid=5 Translation: the longer form of the pronoun (mnie, tobie, jemu) should be used when either: 1. The sentence starts with the pronoun 2. We want to put an emphasis on the pronoun 3. It appears after a preposition (e.g. przy mnie = next to me)
Good to know! I was thrown by the 'jemu' too. I guess it was for emphasis.