Valmiki Ramayana Kishkindha Kanda Sarga 43 Shloka 59
Original Shlokaन कथञ्चन गन्तव्यं कुरूणामुत्तरेण वः। अन्येषामपि भूतानां नातिक्रामति वै गतिः।।4.43.59।।
1 source checked for this shloka
कुरूणामुत्तरेण to the north of Kuru, कथञ्चन however, वः for you, न गन्तव्यम् should not go, अन्येषाम् for other, भूतानाम् अपि other living beings also, गतिः movement, नातिक्रामति transgresses.
'You should not go beyond the north of Kuru. No living being can trespass it.