Sayyiduna Abdullah bin Umar (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "Whoever keeps a dog other than a dog for guarding livestock or a hunting dog, one qirat will be deducted from his reward every day." In one chain the wording is "qirat" (one qirat) and in another "qiratan" (two qirats).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 11024