How To Focus In Salah?

If you didn't focus on Salah then you didn't pray. One day when one of the companion of Prophet Muhammad (Peace be upon him) after praying came to Prophet Muhammad (Peace be upon him) and said Assalamu Alaikum  Prophet Muhammad (Peace be upon him) replied Wa Alaikum Salam and Prophet Muhammad (Peace be upon him) said you didn't pray go and pray again and three times same answer ways said by Prophet Muhammad (Peace be upon him) after that companion said to Prophet Muhammad (Peace be upon him) teach me how to pray because he rushed in Salah he companion didn't focus on prayer