For example, one popular rule that is believed to be scripturally imposed is that brahmanas can't participate in sea voyages. Where is it mentioned that such journey is prohibited?
Where is it mentioned that such journey is prohibited?
Chapter 22, "Varnasramavidhi" (Rules to be followed by four Varnas) of Brihan Naradiya Purana states "Samudrayatra" (voyage over sea) is prohibited for Dvijas (twice borns) in Kali Yuga.
This chapter mentions various deeds which are prohibited in Kali Yuga.
समुद्रयात्रास्वीकारः कमण्डलुविधारणम् । द्वीजानामसवर्णसुवा कन्यास्पयमस्तथा ॥ १३
samudrayātrāsvīkāraḥ kamaṇḍaluvidhāraṇam । dvījānāmasavarṇasuvā kanyāspayamastathā ॥ 13
Undertaking sea voyages, the carrying of kamandalu (waterpot) , the marriage of dvija (twice-born) men with damsels unequal in Varna...
After mentioning all examples, verse 23 (b) says all these practices must be shunned in age of Kali.