In this chapter, David flees to Ahimelech the priest and then to Gath in Philistia.
David has fled from Gibeah of Benjamin (where Saul resided) and now he's in desperate need of help. Like any of us would be if we had to flee our house overnight and go live in the wilderness, David visits one of his friends, Ahimelech the priest, who was in Nob. This is the first time (and nearly the last time) that we will hear any references to Nob, so it must have been the location of the tabernacle at the time, but it is not a prominent city in biblical history. David asks for two things: bread and a sword. Both of these requests are deeply pragmatic, but at the same time I think there is also a lot of symbolism in how he gets it.
David is near the tabernacle, asking one of the chief priests for bread and a sword, and what he gets are the consecrated bread of the presence and the sword of Goliath.
A brief interlude: to those who don't know or remember, the bread of the presence was one of the several things that the LORD commanded Israel to put in the holy place in the tabernacle. It is first mentioned in Exodus 25:23-30, which details a golden table that Israel must build and put in the tabernacle, and Lev 24:5-9 elaborates on this law. It says that 12 fresh loaves of bread should be placed on the table every Sabbath, and the old bread is given to the priests to eat. The bread that Ahimelech gives to David is the bread "which was removed from before the LORD". Lev 24 also says that the bread is holy, which explains why Ahimelech insists that David and his (fictional) men should have kept themselves from women, because sex is one of the things that results in ceremonial impurity (Lev 15:18).
Going back to what I was talking about before, the sword of Goliath is symbolic of David's victory over Goliath and by extension, the LORD's protection over his life. The bread of the Presence is symbolic of the LORD's provision, but given its position in the tabernacle I think it's more likely that it is intended as an allusion to Deut 8:3, where Moses says that man does not live on bread alone, but upon every word that proceeds from the mouth of God. It's also called the bread of the presence, so its name additionally refers to the LORD's presence. But I think that because the bread is replaced every week and is meant to be kept fresh, it is most closely related to the manna of Deut 8:3 that was freshly given to the Israelites every day and by extension, the LORD's commands and voice that guided them through the wilderness.
David is about to go into one such wilderness; both a literal and metaphorical wilderness. The literal wilderness is the Judean Negev desert; the metaphorical one is spending years of his life running away from Saul and with few companions or luxuries, holding only the promise that was given by Samuel when he was anointed to be the next king.
So that's what I think is most interesting about this chapter, how David's requests to Ahimelech are very practical, while at the same time the results are very symbolic. I think this is another area where we can see that the LORD is going to protect David and bring David into the things that he was promised.
Some other things I find interesting are how Ahimelech trembles when he meets with David, asking why David was traveling alone. This is interesting to me because the last time we saw people trembling at the approach of a stranger was when Samuel visited Bethlehem to anoint a son of Jesse to be the next king. Now it is the priest trembling at David's approach, which surprises me a bit because I would have expected these men to know each other.
David, for his part, lies to Ahimelech and says that he is on a king's mission. I'm not sure why he lied, other than perhaps he is afraid that Ahimelech will not help him or try to stop him if he knows the truth. Unfortunately, David's lie means that Ahimelech will later die. Verse 7 tells us that one of Saul's servants, an Edomite of all things (a nation that is hostile to Israel), is present when David sees Ahimelech.
David flees, as we can see in verse 10, but Ahimelech remains because he doesn't know anything is wrong. Saul, in his madness, will later kill Ahimelech as retributive punishment.
Lastly, I wanted to mention a couple things about David's time in Gath. It is strange that David would flee to Gath, which is part of the Philistine confederacy, and what's more, it's the hometown of Goliath whom David slew! How strange is it that David would seek shelter in the town of the great giant that he battled just 4 chapters ago. I don't know why David would think he would be safe here, other than that the Philistines are at war with Israel so he is definitely beyond Saul's reach in this territory. Unfortunately, as we can see Achish's servants remember the Israelite songs of chapter 18, and they wonder why Achish should allow an Israelite hero to remain in their town. There's something very interesting in verse 11 though: Achish's servants call David "the king of the land". He's actually not; Saul is the king of the land, but I think this is significant foreshadowing and possibly also shows popular perception at the time. This might be why Saul is so keen on killing David.
David correctly realizes that he's at just as great a risk from the Philistines as from Saul, but his response is bizarre and humerous. He starts drooling and scribbling on the doors, and Achish's response is similarly funny to me: he is like, "Do I have a shortage of crazy people that you thought you needed to bring me another one?" To me this whole exchange is pretty funny, but it's also weirdly serious because David really could have been executed by Achish. Instead, David escapes and runs off into the wilderness to avoid both Saul and the Philistines.