Each time David saw Goliath's armour hanging in his tent, it was a sacred reminder of God's faithfulness to him and of God's power that was available to him. The word remember recurs almost 250 times in Scripture. And there is a reason why. We tend to remember what we should forget and forget what we should remember. That's why God tells us to build altars or make memorials. Jacob built an altar at Bethel, where God gave him a life-changing dream (see Genesis 28:18-22). The Israelites took twelve stones from the river Jordan and used them to build a miracle altar in Gilgal, reminding them of how God miraculously parted the waters for them (see Joshua 4:20-24). Samuel built a victory altar at Mizpah called 'Ebenezer' after God answered his prayer and marshalled the forces of nature to supernaturally defeat the Philistines (see 1 Samuel 7:12).
Without sacred reminders, we could forget the spiritual lessons we have learned along the way. The Bible records the literal weight of Goliath's armour: 5,000 shekels of brass or 56.7 kilograms. Every time David took down his tent and pitched it somewhere else, the armour went with him. Why? Because it was a daily reminder of God's faithfulness to him. It was also a great confidence builder. Whatever the future held, David knew that with God's help he could handle it.
There are two lessons here: first, if God did it for David, he will do it for you; second, if God did it before, he can do it again.
— SCRIPTURE —
'David...kept Goliath's armour in his tent.' 1 Samuel 17:54 GWT
— SOULFOOD —
2 Ki 4:18-6:33, Luke 13:18-35, Ps 136:1-12, Pro 6:30-31