Development and use of Artificial Intelligence (AI) based systems are growing at a fast pace in our society, simultaneously ethical concerns are arising from them. Addressing AI ethics is a continual issue and has provoked much debate among researchers. The aim of this work is to provide a Guide for Artificial Intelligence Ethical Requirements Elicitation (RE4AI Ethical Guide). The Design Science Research methodology was adopted in order to understand the problem, develop a prototype and evaluate it through a survey. The proposed Guide, composed of 26 cards along 11 ethical principles, is both useful and practical and can help in the elicitation of ethical requirements for AI in the context of agile development. Our preliminary results reveal that the Guide contributes to bridging the gap between high-level and abstract principles and practice by assisting developers and Product Owners to elicit ethical requirements and implement ethics in AI.