Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 5 · Portents, Comets
ग्रहचारः केतवश्च
भिषक्तरंगवाणिज्यवृत्तीनां नाशकृत्तदा ।पूर्वात्रयेचरन्सौम्यो योगतारां भिनत्ति चेत् ॥ ४३ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 56, verse 43.
... then may harm the living of doctors, seafarers and traders. Mercury moving in the three Purvas may split the yogatara (the chief star of a nakshatra) ...
Simple meaning: Mercury in those stars may harm the work of doctors, seafarers and traders.
क्षुच्छस्त्रानलचौरेभ्यो भयदः प्राणिनां तदा ।
Mercury splitting a Purva star brings fear of hunger and thieves. Its path is natural in four stars.
रौद्रेन्दुसार्पपित्र्येषु ज्ञेया मिश्राह्वया गतिः ।
Mercury's path is mixed in some stars and short in others.
गतिस्तीक्ष्णाजचरणाहिर्बुध्न्यभाश्रिभेषुया ।
Mercury's path is sharp in some stars and Yogantika in others.