Heavy Stuff

"Woe to you, scribes and Pharisees, hypocrites! For you tithe mint and dill and cummin, and have neglected the weightier provisions of the law: justice and
mercy and faithfulness; but these are the things you should have done
without neglecting the others."
Matthew 23:23

It is said that these men preferred the rituals of the ceremonial law, and the traditions of the elders, above the duties of the moral law. They neglected:
acting according to justice, fairness  and equity.
having compassion and showing kindness.
keeping one's word and promise, fidelity.

  Justice, mercy and faithfulness are "heavier" (Greek word, barus--metaphorically: burdensome, severe, weighty) in that they require practical application and demonstration of one's faith. Religious duties are important and not to be neglected, but by themselves they are nothing more than a hollow shell.
"What use is it, my brethren, if a man says he has faith, but he has no works? Can that faith save him? If a brother or sister is without clothing and in need of daily food, and one of you says to them, "Go in peace, be warmed and be filled," and yet you do not give them what is necessary for their body, what
use is that? Even so faith, if it has no works, is dead, being by itself."
James 2:14-17