Contradiction with Leviticus 19:18
While 1 Samuel 30:11 shows David's men helping an abandoned Egyptian, Leviticus 19:18 commands loving your neighbor and not bearing a grudge, implying inconsistency in selective benevolence.
Leviticus 19:18: Thou shalt not avenge, nor bear any grudge against the children of thy people, but thou shalt love thy neighbour as thyself: I [am] the LORD.
Contradiction with Deuteronomy 7:2
1 Samuel 30:11 shows mercy towards an Egyptian slave, whereas Deuteronomy 7:2 commands Israelites to make no covenant and show no mercy to certain peoples.
Deuteronomy 7:2: And when the LORD thy God shall deliver them before thee; thou shalt smite them, [and] utterly destroy them; thou shalt make no covenant with them, nor shew mercy unto them:
Contradiction with Deuteronomy 23:6
While 1 Samuel 30:11 depicts aiding an Egyptian, Deuteronomy 23:6 instructs Israelites not to seek peace or prosperity for certain nations.
Deuteronomy 23:6: Thou shalt not seek their peace nor their prosperity all thy days for ever. [prosperity: Heb. good]