Musannaf Ibn Abi Shayba 35:214

Yahya ibn Sa'id narrated to us, from Sufyan, from 'Asim, from Zirr, from 'Abdullah, who said: "Whoever acquires a dog, except for a hunting dog or a livestock dog, a qirat of his deeds will be diminished every day." And he mentioned that Abu Hanifah said: "There is no harm in keeping one."