Valmiki Ramayana Yuddha Kanda Sarga 42 Shloka 10
Original Shlokaएवमुक्तेतुवचनेरामेणाक्लिष्टकर्मणा । संघर्षमाणाःप्लवगाःसिम्हनादैरनादयन् ।।6.42.10।।
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क्लिष्टकर्मणा one who does not cause sorrow, एवमुक्ते having ordered that way तु, वचने his words, प्लवगाः monkeys, संघर्षमाणाः getting ready for war, सिम्हनादैरनादयन् roared like a lion
Ordered in that way by Rama, who does not cause sorrow, the monkeys roared like lions getting ready for war on hearing Rama's words.