Vaishnava Dharmashastra 87.9

87.9

sasamudraguhā tena saśailavanakānanā
caturantā bhaved dattā pṛthivī nātra saṃśayaḥ //

'That man doubtless obtains the same reward as if he were to bestow the whole earth on him, bordered as it is on every side (by the oceans), together with the oceans and caverns, and with rocks, groves, and forests.