The Israelite them complain too much and it tested Moses meekness (Nu 20:​2-5; w19.02-E 12 ¶19)

One time Moses not control his temper (Nu 20:10; w19.02-E 13 ¶20-21)

Jehovah punish Moses and Aaron for the serious mistake they make (Nu 20:12; w09-E 9/1 19 ¶5)

To be meek it means, to not get vex quick-quick, and to not be proud or selfish. It can make the person to bear anything without getting vex. The person can’t keep thing in their heart or pay their debt when somebody do bad to them.