THE GIFT OF TRUTH EXCELS ALL OTHER GIFTS
Sabba danam dhamma danam jinati sabbam rasam dhamma raso jinati
Sabbam ratim dhamma ratijinati tanhakkhayo sabba dukkham jinati.
The gift of Truth excels all (other) gifts. The flavour of Truth excels all (other) flavours.
The pleasure in Truth excels all (other) pleasures. He who has destroyed craving overcomes all sorrow. 
On one occasion, at a meeting of the devas in the Tavatimsa realm, four questions were raised, but the devas failed to get the correct answers. Eventually, Sakka took those devas to the Buddha at the Jetavana monastery. After explaining their difficulty, Sakka presented the following four questions:-
Among gifts, which is the best?
Among tastes, which is the best?
Among delights, which is the best?
Why is the eradication of craving said to be the most excellent?
To these questions, the Buddha replied, 'The Dhamma is the noblest of all the gifts, the best of all tastes and the best of all delights. Eradication of craving leads to the end of all suffering and is, therefore the greatest of all conquests.'
At the end of the discourse, Sakka said to the Buddha, 'Venerable Sir, if the gift of the Dhamma excels all other gifts, why are we not invited to share the merit whenever gifts of the Dhamma are made? Venerable Sir! I pray that from now on, we may be given a share in the merit of the good deeds.' Then the Buddha asked all the bhikkhus to assemble and exhorted them to share the merits of all their good deeds with all beings.
Since then, it has become a custom to invite all the devas and others toshare the merit*whenever a good deed is done.
*The stanza recited to invite theDevasandNagasto share the merit is:
Akasattha ca bhummattha - Deva Naga mahiddhika
Punnam tam anumoditva - Ciram rakkhantu loka sasanam
May beings, celestial and terrestrial, Devas and Nagas of mighty power, share this merit of ours. May they long protect the world and the Dispensation.