Interesting… … yes, I also would understand ‘an adornment to the mind’ as something connected to joy (necessary for meditation), but in this context I’d sooner take the whole sentence into the picture:
“He does not give a gift, [thinking]: ‘When I am giving a gift my mind becomes placid, and elation and joy arise,’ but rather he gives a gift, [thinking]: ‘It’s an ornament of the mind, an accessory of the mind.’ (Bodhi)
They don’t give a gift thinking, ‘When giving this gift my mind becomes clear, and I become happy and joyful.’ But they give a gift thinking, ‘This is an adornment and requisite for the mind.’ (Sujato)
Having given this, not seeking his own profit, … but with the thought, ‘This is an ornament for the mind, a support for the mind’ (Thanissaro)
They all use the word “thinking/thought”. I read it more as a reflection (and intention setting) that will at some point lead to the brightening of the mind.
Incidentally, Bhikkhu Bodhi further comments:
The three editions have slightly different readings. I follow Ce cittālaṅkāraṃ cittaparikkhāranti. Neither Be nor Ee have the quotation marker ti. Mp: “It is an ornament, an accessory, of the mind pertaining to serenity and insight” (samathavipassanācittassa).
There’s really a point worth pausing on! Much as I’m delighted by Mat’s confidence in the “temporary flash[es] of joy that you get after giving” I’m really not so sure that this is always everyone’s experience. It’s my feeling that it’s better to account for and work with as broad a range of actual experiences (in this case in connection to giving); if an instruction doesn’t resonate, or ‘click’, I reckon it’s probably not going to be all that useful to a practitioner at that time.
I think this is a slightly difference case, here the Buddha seems to be talking about the moral validity of a mendicant accepting a meal and how they should ‘relate’ to the given meal. There is no discussion about the results mendicant’s actions will have on the person offering the meal.
In fact, this is the very reason why I find AN5.45 a little interesting, it essentially suggests that someone else’s actions (or accomplishments) will bring an individual merit. I find it a bit problematic for a couple of reasons, the primary one being that the implication is some degree of an individual’s spiritual happiness can fall outside of the field of their own intention/action.