All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ‘alayhi wa sallam, is His slave and Messenger.
The hadeeth in reference was authentically reported and cited in Saheeh Al-Bukhari. However, it has nothing to do with what you mentioned in the question. You are not obliged to help this person with his work, although it recommended for you to help him if there is no impediment to it and you are able to help him, especially given that he made you some favors in the past. The Islamic Sharia urges Muslims to reward the kindness of people with similar kindness.
Allah knows best.