I will declare your name to my brothers. In the midst of the assembly, I will praise you. — Psalms 22:22
For you will be a witness for him to all men of what you have seen and heard. — Acts 22:15

Author
Charles Spurgeon
Summary: Like Paul, we must first see and hear the Lord; otherwise, we will have nothing to communicate. But what we receive must not remain hidden: divine revelation is granted to us so that we may influence others through our testimony. This testimony must be personal, centered on Christ, constant, and so all-absorbing that it takes precedence over many other things. Nor should we limit it to those who gladly receive it, but bring it to all whom we can reach: young and old, rich and poor, good and bad. The word of the LORD is both a command and a promise; therefore, we must not remain silent, but ask that it may also be fulfilled in us.
Paul was chosen to see and hear the Lord speaking to him from heaven. This divine choice was a lofty privilege for Paul; but it was not intended to end there; rather, its purpose was for him to exert an influence upon others; yes, upon all men
. It is to Paul that the world owes the Gospel at this hour.
It is our duty, in our measure, to be witnesses of what the Lord has revealed to us, and we conceal that precious revelation at our own peril. First, we must see and hear, for otherwise we would have nothing to say; but once we have done that, we must be eager to give our testimony. It must be personal: "You shall be." It must be for Christ: "You shall be His witness." It must be constant and completely all-absorbing; we must be this above all other things and to the exclusion of many other things. Our testimony must not be for a select few who receive us gladly, but for "all men," everyone we can reach, young or old, rich or poor, good or bad. We must never remain silent like those possessed by a mute spirit; for the text before us is a command and a promise, and we must not let it slip away: "You shall be His witness." "You are My witnesses, says Jehovah."
Lord, fulfill this word for me too
Source: http://www.spurgeon.com.mx/chequera/meditames/febrero.pdf
The Cheque Book of the Bank of Faith. Translated by Allan Román.