Mahabharata 13.57.16

शय्यासनानि यानानि योगयुक्ते तपोधनेअग्निप्रवेशे नियतं ब्रह्मलोको विधीयते

śayyāsanāni yānāni yogayukte tapodhaneagnipraveśe niyataṃ brahmaloko vidhīyate

Our plain-language meaning of this verse is waiting for scholar review.