Reply to Objection 3: We have no authority for supposing that the double cave which Abraham bought for a burial place was consecrated for that purpose: wherefore Abraham could lawfully buy that site to be used for burial, in order to turn it into a sepulchre: even so it would be lawful now to buy an ordinary field as a site for a cemetery or even a church. Nevertheless because even among the Gentiles burial places are looked upon as religious, if Ephron intended to accept the price as payment for a burial place, he sinned in selling, though Abraham did not sin in buying, because he intended merely to buy an ordinary plot of ground. Even now, it is lawful in a case of necessity to sell or buy land on which there has previously been a church, as we have also said with regard to sacred vessels (Reply Objection [2]). Or again, Abraham is to be excused because he thus freed himself of a grievance. For although Ephron offered him the burial place for nothing, Abraham deemed that he could not accept it gratis without prejudice to himself.
The right of the first-born was due to Jacob by reason of God's choice, according to Malach. 1:2,3, "I have loved Jacob, but have hated Esau." Wherefore Esau sinned by selling his birthright, yet Jacob sinned not in buying, because he is understood to have freed himself of his grievance.
The right of patronage cannot be the matter of a direct sale, nor can it be granted "in fee," but is transferred with the property sold or granted.
The spiritual right of receiving tithes is not granted to layfolk, but merely the temporal commodities which are granted in the name of tithe, as stated above (Question [87], Article [3]).
With regard to the granting of benefices it must, however, be observed, that it is not unlawful for a bishop, before presenting a person to a benefice, to decide, for some reason, to retain part of the revenues of the benefice in question, and to spend it on some pious object. But, on the other hand, if he were to require part of the revenues of that benefice to be given to him by the beneficiary, it would be the same as though he demanded payment from him, and he would not escape the guilt of simony.