Bhashya
तयोः तकारसामान्यात् ।तदेतत् अनृतं तकाराक्षरं मृत्यु-रूपम् उभयतः सत्येन सकारयकारलक्षणेन परिगृहीतं व्या-प्तम् अन्तर्भावितं सत्यरूपाभ्याम्, अतः अकिञ्चित्करं तत्,सत्यभूयमेव सत्यबाहुल्यमेव भवति ; एवं सत्यबाहुल्यं सर्व-स्य मृत्योरनृतस्य अकिञ्चित्करत्वं च यो विद्वान्, तमेवं वि-द्वांसम् अनृतं कदाचित् प्रमादोक्तं न हिनस्ति ॥
In plain words
The two words share that single letter 't' — that is the whole clue. The syllable of untruth, 't', carries death in it, but truth closes in on it from both sides, the letters 's' and 'y', soaking it through, taking it up into itself. It is left with no power to do anything. What remains is truth — overwhelmingly truth. Know this: that truth outweighs everything, and that this death-bound sliver of untruth has no force of its own — and if you slip and speak a falsehood by accident, it will never be able to touch you.
Close to the Sanskrit
[This is] because of the two words sharing the letter 't'. This untruth, the syllable 't', has the nature of death; it is seized on both sides by truth, marked by the letters 's' and 'y', pervaded, absorbed within the two forms of truth. Therefore it is powerless. It becomes truth-predominant, truth-abundant indeed. Thus, one who knows this abundance of truth in everything, and the powerlessness of mortal untruth — such a knower is never harmed by an untruth spoken by accident at some time.