"Beware of practicing your piety before men in order to be seen by them; for then you will have no reward from your Father who is in heaven."Beware of practicing your piety before men in order to be seen by them; for then you will have no reward from your Father who is in heaven.
"Thus, when you give alms, sound no trumpet before you, as the hypocrites do in the synagogues and in the streets, that they may be praised by men. Truly, I say to you, they have their reward. But when you give alms, do not let your left hand know what your right hand is doing, so that your alms may be in secret; and your Father who sees in secret will reward you.
"And when you pray, you must not be like the hypocrites; for they love to stand and pray in the synagogues and at the street corners, that they may be seen by men. Truly, I say to you, they have their reward. But when you pray, go into your room and shut the door and pray to your Father who is in secret; and your Father who sees in secret will reward you.
"And in praying do not heap up empty phrases as the Gentiles do; for they think that they will be heard for their many words. Do not be like them, for your Father knows what you need before you ask him. Pray then like this:
Our Father who art in heaven,
Hallowed be thy name.
Thy kingdom come,
Thy will be done,
On earth as it is in heaven.
Give us this day our daily bread;
And forgive us our debts,
As we also have forgiven our debtors;
And lead us not into temptation,
But deliver us from evil.
- Matthew 6:1-13
Our Lord warns His disciples against giving alms from a motive of ostentation, and against making long prayers in public with the object of being seen and admired by men.
If a man gives alms he always receives a reward. If he does it in order to gain human praise, he has the reward he seeks, but from God he receives no reward, but only a punishment for his pride and his desire to gain honour from men. How careful then I must be that when I give alms, it is not done to gain gratitude, or with a desire to be thought highly of, or from mere natural generosity, since thus I gain no reward from God, but, it may be, only call down His anger on me.
When we pray in public, or go to Mass when there is no obligation, the thought sometimes comes into our minds that others must be edified by our piety and must admire our devotion. We cannot prevent the thought presenting itself, there is no sin in that, but we must repel it to the best of our ability by dwelling on our own misery, and what we are in God's sight. Such a thought, if indulged deliberately, mars even the most pious prayer, and sometimes takes away all its merit before God, and is an offence, not an honour to Him.
Ought we to abstain from prayer, from Holy Communion, from any practice of devotion, because thoughts of vanity come in? Certainly not. Our rule should be to act in the presence of others just as if they were not there. If the temptation to vanity comes, say to the devil with Saint Bernard: "I did not begin for you, and I will not leave off for you!"
- taken from The Ministry of Jesus Christ: Short Meditations on the Public Life of Our Lord, by Father Richard Frederick Clarke, SJ