Matthew 6
Giving in secret
Take heed that ye do not your alms before men, to be seen of them: otherwise ye have no reward of your Father which is in heaven. Therefore when thou doest thine alms, do not sound a trumpet before thee, as the hypocrites do in the synagogues and in the streets, that they may have glory of men. Verily I say unto you, They have their reward. But when thou doest alms, let not thy left hand know what thy right hand doeth: That thine alms may be in secret: and thy Father which seeth in secret himself shall reward thee openly.
Jesus warns against doing religious deeds to be seen by others. When giving to the poor, his hearers should do it so quietly that their left hand does not know what the right is doing; their Father, who sees in secret, will reward them.
What does this mean?
'Alms' (KJV) are gifts to the poor; WEB has 'charitable giving' and 'merciful deeds'. 'Hypocrite' was the Greek word for a stage actor, someone playing a part for an audience. 'Sound a trumpet' is probably a figure of speech for drawing attention to oneself.
Historical context
Giving to the poor, prayer and fasting were three central practices of Jewish piety, and almsgiving was regarded as a basic religious duty.
Why does it matter?
This opens a three-part section on giving, prayer and fasting, each following the same pattern: not like the hypocrites, but in secret, and the Father will reward. The Lord's Prayer sits at its centre.
Editorial notes, not scripture.