Valmiki Ramayana Kishkindha Kanda Sarga 54 Shloka 13
Original Shlokaयां चेमां मन्यसे धात्रीमेतद्बिलमिति श्रुतम्। एतल्लक्ष्मणबाणानामीषत्कार्यं विदारणे।।4.54.13।।
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याम् whichever, इमाम् this, धात्रीम् earth, मन्यसे you may be thinking, एतत् this, बिलम् cave, इति in this way, श्रुतम् is known, लक्ष्मणबाणानाम् for the arrows of Lakshmana, एतत् this, विदारणम् breaking, ईषत्कार्यम् is a very small task.
'You may think it safe to stay here in this opening of the earth. It is a petty task for the arrows of Lakshmana to break open this socalled cave.