4:13  

चातुर्वर्ण्यं मया सृष्टं गुणकर्मविभागशः ।
तस्य कर्तारमपि मां विद्ध्यकर्तारमव्ययम् ॥४-१३॥

chaaturwarNyaM mayaa sRRiShTaM guNakarmawibhaagashaH ।

tasya kartaaramapi maaM widdhyakartaaramawyayam ॥४-१३॥

Source: Automatic ITRANS Transliteration

Four castes were created by Me according to their qualities and actions.
Know Me, though the maker of these, the imperishable non-maker.

I created four castes according to their [members'] qualities and actions. Realize that though I am the maker of these, I am the imperishable non-maker.

Source: Milind S. Pandit

The four Varna or divisions of human society, based on aptitude and vocation, were created by Me. Though I am the author of this system, one should know that I do nothing and I am eternal. (See also 18.41)

Source: The Bhagavad-Gita: The Sacred Song

According to the three modes of material nature and the work ascribed to them, the four divisions of human society were created by Me. And, although I am the creator of this system, you should know that I am yet the non-doer, being unchangeable.

Source: Bhagavad Gita As It Is