B.G 18.15 and 16
शरीरवाङ्मनोभिर्यत् कर्म प्रारभते नरः। न्याय्यं वा विपरीतं वा पञ्चैते तस्य हेतवः ॥१५॥
Whatever action a man performs with his body, speech, and mind, whether it is just or unjust, these five are its causes.
तत्रैवं सति कर्तारं आत्मानं केवलं तु यः। पश्यत्यकृतबुदि्धत्वान्न स पश्यति दुर्मतिः ॥१६॥
In this situation, the one who perceives the Ātmān, the Lord, as inactive (merely active), due to lack of wisdom, does not truly see, as he is misguided.
Gīta Bhāshya 18.15 and 16
'kartāraṃ ātmānaṃ kevalaṃ' - translates to one who perceives 'Ātmān as merely active, i.e. inactive. One who overlooks the omnipotent aspect of the Lord is foolish.
केवलं निष्क्रियम्। एनं केवलमात्मानं निष्क्रियत्वाद्वदन्ति हि॥ इति तत्रैव॥
The word 'kevalam' i.e. limiting, in the context means inactivity. They say - this mere Ātmān is indeed inactive. Hence, the verse 'tatraivaṃ'.