Maintain an upright posture while bowing and prostrating during prayer.

The hadith narrated by Abu Mas'ud teaches us about the importance of maintaining an upright posture during prayer. According to the Prophet Muhammad, a prayer is not valid if one does not keep their back straight when bowing and prostrating. This means that when we are praying, we should be mindful of our posture and make sure that our backs are straight so that our prayers can be accepted by Allah. It is important to remember this teaching as it shows us how important it is to take care of ourselves while worshipping Allah. We should also strive to maintain good posture in all aspects of life, as this will help us stay healthy and strong both physically and spiritually.