What were both nobles and knights obligated?

Both nobles and knights were obligated to provide military service to their lord or king, ensuring protection and defense of the realm. Nobles, as landowners, were responsible for managing their estates and contributing resources, while knights, as vassals, were expected to serve in battle and uphold chivalric values. Additionally, both were expected to maintain loyalty and support their lord in political and social matters. In return, they received land, titles, and protection.