For D1, see 13.1.1.3 of the Manual. For D2, see 13.1.1.2.
The rules are the same for both divisions:
" An athletics staff member or other representative of the institution’s athletics interests shall not make contact with the student-athlete of an NCAA or NAIA four-year collegiate institution, directly or indirectly, without first obtaining the written permission of the first institution’s athletics director (or an athletics administrator designated by the athletics director) to do so, regardless of who makes the initial contact. If permission is not granted, the second institution shall not encourage the transfer and shall not provide athletically related financial assistance to the student-athlete until the student-athlete has attended the second institution for one academic year. If permission is granted to contact the student-athlete, all applicable NCAA recruiting rules apply."
There is also an appeal procedure if the first school refuses to allow the transfer, but I don't understand how it could be enforced against a NAIA school.
I don't know for sure, but I believe that a violation of this rule would be an instance of an institutional violation, but wouldn't affect an athlete's eligibility. It probably would eliminate the possibility of financial aid during the first year.
NCAA Manuals