When David became the great and beloved king of Israel, he ordered new gold and silver coins to be minted.
"Be sure to give the coins their full weight, so that my people may deal honestly with each other," David warned his ministers.
"And what, Your Majesty, shall be your emblem on the new coins?" asked the ministers.
"A tower (the Tower of David) should be placed on one side of the coins.
The ministers were very pleased. But they were not a little surprised when the king continued-
"And on the other - a shepherd's staff and shepherd's bag."
The ministers went to work and before long, off came shiny new coins of gold and silver. Everybody was anxious to see and own the new coins, for they were honest and had their full weight. The coins spread to other lands too, for merchants would have David's coins rather than any others.
But what people liked most about these coins were the "heads" and "tails" of them. "Look!" they said to one another. "The great and mighty David, whom G‑d had chosen and anointed, is not ashamed of his humble origin. Nay, he never forgets that G‑d had taken him from his flocks of sheep and made him king. He has other flock to care for now, and he treats them as lovingly and as tenderly as he had treated his little lambs!"
And in all foreign lands, where the people suffered under the reign of cruel tyrants, people admired King David's coins, sighed and said: "How good it is to be an Israelite and have such a wonderful and lovely king!"
I can't actually find reference to this in the scripture, could you point me to the actual passage?
The scriptural reference is found in the verse, "And I will make of you a great nation; I will bless you, and I will make your name great, and you will be a blessing." (Genesis 12:2)
The Midrash (Bereshit Rabbah 39:11) explains:
"There are four people whose images appeared on coins that circulated in the world. Abraham – “I will make you a great nation”(ibid)... Joshua – “The Lord was with Joshua; his fame was throughout the land” (Joshua 6:27)...David – “David’s renown circulated in all lands” (I Chronicles 14:17) – his image circulated on coins in the world. What was the image on his coin? It was a [shepherd’s] staff and satchel on one side, and a tower on the other side, after: “Your neck is like the tower of David” (Song of Songs 4:4)...Mordechai – “For Mordechai was great in the king’s palace, and his renown spread in all the provinces” (Esther 9:4)..."