¶1It is an undisputed fact, that the Moores expressly assumed and promised to pay the amount of the mortgage debt due to the appellee from Dulaney and wife, as a pax't of the purchase-money of the prexnises. It is also undisputed, that the amount was deducted from the purchase-money they had contracted and were bound to pay presently. "Whether the debt was binding on Mrs. Dulaney, or the mortgage was valid and operative as a security, as between the appellee and Mrs. Dulaney, is not now a material question. The only title which the Moores acquired, by their own agreement, on a full axxd fair consideration, they subordinated to the mortgage, and they are now estopped from disputing its validity. — Bunkley v. Lynch, 47 Ala. 211; Comstock v. Smith, 26 Mich. 306; Freeman v. Auld, 44 N. Y. 50; 1 Jones on Mortgages, §§ 749-754. Whether the verbal agreement that the appellee should have a vendor’s lien on the lands, as a security for the debt, can be enforced, it is not necessary to inquire. The invalidity of that agreement can not lessen the liability of- the Moores to pay the debt, or if they do not, to allow the lands to be applied to its payment.
¶2The estoppel resting on the Moores is equally binding on the appellant, who has merely succeeded to their rights, and to whom the registration of the mortgage was constructive notice. A person claiming title under one who is es-topped, in the absence of some superior equity, is bound by the estoppel. — McCravey v. Remson, 19 Ala. 430; Sikes v. Basnight, 2 Der. & Bat. (Law) 157.
¶3There is no error in the record prejudicial to the appellant, and the decree is affirmed.