BṚHADĀRAṆYAKA UPANISHAD · 6.4.9

स याम् इच्छेत् -- कामयेत मेति तस्याम् अर्थं निष्ठाय मुखेन मुखं संधायोपस्थम् अस्या अभिमृश्य जपेत् --
अङ्गाद् अङ्गात् संभवसि हृदयाद् अधिजायसे ।
स त्वम् अङ्गकषायो ऽसि दिग्धविद्धाम् इव मादयेमाम् अमूं मयीति ॥

sa yām icchet -- kāmayeta meti tasyām arthaṃ niṣṭhāya mukhena mukhaṃ saṃdhāyopastham asyā abhimṛśya japet --
aṅgād aṅgāt saṃbhavasi hṛdayād adhijāyase ।
sa tvam aṅgakaṣāyo ’si digdhaviddhām iva mādayemām amūṃ mayīti ॥

The woman whom one may desire with the thought, 'May she enjoy love with me!'--after coming together with her, joining mouth with mouth, and stroking her lap, he should mutter:-- 'Thou that from every limb art come, That from the heart art generate, Thou art the essence of the limbs! Distract this woman here in me, As if by poisoned arrow pierced!'

Robert Ernest Hume · The Thirteen Principal Upanishads (1921), Bṛhadāraṇyaka VI.4