Imam al-Shafi'i (may Allah have mercy on him) said: "And since they, meaning the people of desires (innovators), are like this (acceptable in testimony), then the one who plays chess, even though we dislike it for him, and the one who plays with pigeons, even though we dislike it for him, is in a lighter state than these people by a degree that can be neither counted nor estimated."
Imam al-Shafi'i (may Allah have mercy on him) said this because in this (issue of chess) too there is a difference of opinion among the scholars.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الشهادات / Q20922