John Gill Commentary Joshua 24:14

"Now therefore fear Jehovah, and serve him in sincerity and in truth; and put away the gods which your fathers served beyond the River, and in Egypt; and serve ye Jehovah." — Joshua 24:14 (ASV)

Now therefore fear the Lord
Since he has done such great and good things, fear the Lord and his goodness, fear him for his goodness sake; nothing so influences fear, or a reverential affection for God, as a sense of his goodness; this engages men sensible of it to fear the Lord, that is, to worship him both internally and externally in the exercise of every grace, and in the performance of every duty:

and serve him in sincerity and in truth :
in the uprightness of their souls, without hypocrisy and deceit, and according to the truth of his word, and of his mind and will revealed in it, without any mixture of superstition and will worship, or of the commands and inventions of men:

and put away the gods which your fathers served on the other side of
the flood, and in Egypt ;
that is, express an abhorrence of them, and keep at a distance from them, and show that you are far from giving in to such idolatries your ancestors were guilty of, when they lived on the other side Euphrates, in Chaldea, or when they were sojourners in Egypt; for it cannot be thought that the Israelites were at this time guilty of such gross idolatry, at least openly, since Joshua had borne such a testimony of them, that they had cleaved to the Lord unto that day, (Joshua 23:8) ; and their zeal against the two tribes and a half, on suspicion of idolatry, or of going into it, is a proof of it also:

and serve you the Lord :
and him only.