Article — Wouters, Manual of Moral Theology
Article IV. On Abuses to Be Avoided in Accepting Stipends
From Mass stipends, thus canon 827, every kind even of negotiation or commerce is altogether to be kept away. This canon is neglected: 1. by those who of their own accord retain part of the stipend (n. 227); 2. by those who ask others that, when Masses have been transferred, they may retain part of the stipend (n. 227); 3. by booksellers or merchants who collect stipends and, in place of them, give books, periodicals, or other merchandise to priests who are going to celebrate the Masses,1 whether with profit (commerce) or without profit (a species of commerce). The author of the stipend, however, can offer other things to the one who is going to celebrate, in place of money.
1 Decree Ut debita of the Sacred Congregation of the Council, 11 May 1904 (article 8); cf. Sacred Congregation of the Council, 9 September 1874; decree Vigilanti studio, 23 May 1893.