It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: The price of a dog is forbidden. When someone comes to demand the price of a dog, fill his hands with dust.
Hadith Referenceالفتح الربانی / كتاب البيوع والكسب والمعاش وما يتعلق بالتجارة / 5811