“And when you pray, do not be like the hypocrites, for they love to pray standing in the synagogues and on the street corners to be seen by others. Truly I tell you, they have received their reward in full." Matthew 6:5
Jesus said when you pray you should pray sincerely. That means your prayers should be marked by humility, by honesty and they should be heartfelt.
Here is another classic example of a sincere prayer from the Old Testament.