Fran. Max. 9, max. 8 Thus, where an heir buys in an incumbrance for less than is due upon it, (except it be to protect an incumbrance to which he himself is entitled,) he shall be allowed no more than what he really paid for it, as against other incumbrancers upon the estate. 2 Vent. 3358; 1 Vern. 49; 1 Salk. 155.