Mahabharata 1.41.10
तपसोऽस्य चतुर्थेन तृतीयेनापि वा पुनःअर्धेन वापि निस्तर्तुमापदं ब्रूत माचिरम्
tapaso'sya caturthena tṛtīyenāpi vā punaḥardhena vāpi nistartumāpadaṃ brūta māciram
Our plain-language meaning of this verse is waiting for scholar review.
Open in the book