Comparative evidence

h₃rei̯h₁, h₃rei̯h₂, h₃rei̯h₃

• OInd. ri-/rī- 'flow' (Whitney 1885: 139); 'release', 'set free', 'let go'; 'sever', 'detach' (from); 'yield', 'bestow'; 'be shattered', 'be dissolved', 'melt', 'become fluid', 'drop' (MW: 881)

References

MW = Monier-Williams, M. 1899. A Sanskrit-English Dictionary. Clarendon Press.
Whitney 1885 = Whitney W. D. 1885. The roots, verb forms and primary derivatives of the Sanskrit language. A supplement to his Sanskrit grammar. Leipzig.