In plain words
Sannyāsa of obligatory action is not proper. Its abandonment through delusion is declared tāmasa.
Word for word
But the saṃnyāsa of obligatory action is not proper; its abandonment through delusion is declared tāmasa.
नियतस्य तु सन्न्यासः कर्मणो नोपपद्यतेमोहात् तस्य परित्यागस्तामसः परिकीर्तितः
Other commentaries
The commentators
▸Bhagavadgītābhāṣyam
तस्मात् अज्ञस्य अधिकृतस्य मुमुक्षोः —
नियतस्य तु नित्यस्य संन्यासः परित्यागः कर्मणः न उपपद्यते, अज्ञस्य पावनत्वस्य इष्टत्वात् । मोहात् अज्ञानात् तस्य नियतस्य परित्यागः — नियतं च अवश्यं कर्तव्यम् , त्यज्यते च, इति विप्रतिषिद्धम् ; अतः मोहनिमित्तः परित्यागः तामसः परिकीर्तितः मोहश्च तमः इति ॥ ७ ॥
In plain words
So then — for the one who does not yet know, who is qualified to act, and who wants to be free —
Laying down the work that has been fixed for you — the standing, daily work — does not hold up. For someone still ignorant, that very work is what does the purifying, and that is exactly what is intended here. So dropping it comes out of moha, out of plain ignorance. Look at the two statements side by side: the work is obligatory, it has to be done — and the work is being dropped. They cancel each other. That is why renunciation with delusion at its root is called tāmasa. And delusion is nothing but tamas — darkness itself.
Close to the Sanskrit
Therefore, of the one who does not know, of the one who is qualified, of the one who desires liberation —
But the saṃnyāsa — the complete abandonment — of enjoined, that is, of constant, action is not tenable, because in the case of the ignorant its purifying character is what is intended. From delusion, that is, from ignorance, comes the abandonment of that enjoined action — 'the enjoined is necessarily to be done', and 'it is being abandoned': this is self-contradictory. Therefore abandonment having delusion for its cause is declared tāmasa; and delusion is darkness.