Valmiki Ramayana Ayodhya Kanda Sarga 52 Shloka 72
Original Shlokaअप्रमत्तो बले कोशे दुर्गे जनपदे तथा। भवेथा गुह राज्यं हि दुरारक्षतमं मतम्।।2.52.72।।
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गुह Guha, बले in the army, कोशे in the treasury, दुर्गे in the fort, तथा similarly, जनपदे in the provinces, अप्रमत्तः alert, भवेथाः you shall be, राज्यम् kingdom, दुरारक्षतमम् with great difficulty, मतं हि it is said.
O Guha you must be vigilant about your army, treasury, forts and provinces. A kingdom, it is (rightly) said, is protected with great difficulty.