Final answer:
The primary rule of conduct in regard to foreign nations, according to George Washington's Farewell Address, was to have as little political connection as possible with foreign nations.
Step-by-step explanation:
The primary rule of conduct in regard to foreign nations, according to George Washington's Farewell Address, was to have as little political connection as possible with foreign nations. Washington emphasized the importance of maintaining good faith, justice, peace, and harmony with all nations, while avoiding frequent controversies and forming artificial ties in the politics of foreign nations.