Canto 3 -
Araṇya-kāṇḍa
Chapter 40: Rāvaṇa Criticizes Mārīca
Text 3.40.16

अस्मिंस्तु त्वं महाकृत्ये साहाय्यं कर्तुमर्हसि।
शृणु तत्कर्म साहाय्ये यत्कार्यं वचनान्मम॥

asmiṁs tu tvaṁ mahā-kṛtye sāhāyyaṁ kartum arhasi
śṛṇu tat karma sāhāyye yat kāryaṁ vacanān mama

asmin tu = in this; tvam = you; mahā-kṛtye = great task; sāhāyyam kartum arhasi = should assist [me]; śṛṇu = hear; tat = about that; karma = activity; sāhāyye = for assisting [me]; yat = which; kāryam = [you] should do; vacanāt = on order; mama = my.

You should assist [me] in this great task. Hear about that activity which [you] should do for assisting [me] on my order.