Why did the news about God’s blessing on the household of Obed-edom prompt David to go and bring the ark to Jerusalem?
When David heard about the blessing which had come upon Obed-edom, he realized that the same blessing could also come to Jerusalem if the ark was to be housed in the city.1 The Lord was not necessarily against his plans to move the ark but he had to make sure to move it in an appropriate manner.
12 And it was told King David, “The LORD has blessed the household of Obed-edom and all that belongs to him, because of the ark of God.” So David went and brought up the ark of God from the house of Obed-edom to the city of David with rejoicing.