4:2  

एवं परम्पराप्राप्तमिमं राजर्षयो विदुः ।
स कालेनेह महता योगो नष्टः परन्तप ॥४-२॥

ewaM paramparaapraaptamimaM raajarShayo widuH ।

sa kaaleneha mahataa yogo naShTaH parantapa ॥४-२॥

Source: Automatic ITRANS Transliteration

Thus, traditionally receiving it, this became known to sage-kings.
After a long time now, this yoga has perished, O foe-scorcher.

Thus, this yoga became known to sage-kings who received it by tradition. O foe-scorcher, after a long time, this yoga has now perished.

Source: Milind S. Pandit

Thus handed down in succession the royal sages knew this (Karma-yoga). After a long time the science of Karma-yoga was lost from this earth.

Source: The Bhagavad-Gita: The Sacred Song

This supreme science was thus received through the chain of disciplic succession, and the saintly kings understood it in that way. But in course of time the succession was broken, and therefore the science as it is appears to be lost.

Source: Bhagavad Gita As It Is