Why do we anumodana (rejoice) in the good deeds of others and its results in the afterlife

Why do we anumodana (rejoice) in the good deeds of others and its results in the afterlife 

Perhaps we have some very wealthy or generous Dhamma friends. For instance, we have brother Kelvin who likes to raise funds for the Sangha. 

Sometimes when such friends perform some dana, we will say "Anumodana Sadhu!" to them. Don't worry that you aren't wealthy enough, and can't find enough spare cash to donate. When you anumodana and find joy in the good deeds of others - this pure intention is powerful enough to provide you with a heavenly rebirth.  

In the Vihāra Vimāna Sutta of the Khuddaka Nikaya, Phra Anuruddha came across a deva of amazing appearance in the Heavenly Realm of Thirty Three (Tavatimsa - 2nd Lowest out of 6 Heavens), in fact, her beauty, fragrance, music, surpasses that of most other devas and her companions. He was curious and asked her, "What kind of meritorious actions did you do to have gained these results?" 

This was her reply.

"Bhante, in the human world I had a friend [Visakha - Buddha's most generous female patron] who lived in the city of Savatthi. She built a great monastery for the community of monks. I was extremely happy about that. I sincerely rejoiced in her gift and the merit that she gained. The sight of that monastery was pleasing to my eyes.

As a result of truly rejoicing in my friend’s meritorious deed, this wonderful divine mansion has appeared for me.

Due to the power of my meritorious deed, this divine mansion spreads for sixteen kilometers into the sky and shines brightly in all directions. In my mansion, there are huge rooms divided into sections.

There are lotus ponds filled with heavenly fish. The water in the pond is clear, filled with many kinds of lotuses that give off a sweet smell when the wind blows. The banks of the pond are covered with golden sand.

Inside my mansion grow all sorts of trees: rose-apples, jackfruits, palms and coconuts. I am surrounded by beautiful music and the sound of many goddesses. Even if someone sees me only in a dream they will be happy.

A mansion like mine, excellent, beautiful and gleaming, has been created for me because of my meritorious deeds. This is why we should do good actions."

Phra Anuruddha was still curious, so he asked, "Since you rejoiced in your friend’s excellent gift, you have received this beautiful mansion. Tell me what happened to your friend. 

Where was she reborn?"

The deva replied, "That friend of mine offered that large monastery for the Noble Sangha. She understood the Four Noble Truths clearly and made offerings with that understanding. 

She was reborn in the Nimmanarati Heaven [5th Highest Heaven, 3 Heavens higher than Tavatimsa]. She is now the chief queen of Sunimmita, king of that heaven. I can’t even imagine the sensual pleasures she is now enjoying because of her gift. You asked me where she was reborn, and I told you as it is.

After hearing about the results of this gift, tell others to happily give gifts to the Noble Sangha and listen to the Dhamma with minds of faith. To be born as a human is very rare, and now you have this chance.

The Supreme Buddha, with golden skin and a sweet voice, taught us this excellent way: happily give gifts to the Noble Sangha, where gifts give the best results.

The Noble Sangha has eight kinds of people grouped in four pairs. These disciples of the Buddha are worthy of gifts. Gifts given to them will be of great fruit: Stream-Enterer, Once-Returner, Non-Returner, Arahant, and the other four who are on the path to these states. The Noble Sangha is true to their purpose with concentration, wisdom, and morality.

Human beings give alms wanting to make merit. The merit they gain when giving to the Noble Sangha will bear fruitful results in their future lives.

The Noble Sangha is full of goodness and has become great. It is impossible to measure its greatness, just as it is impossible to measure the water in the ocean. Followers of the Great Hero, the Supreme Buddha, are the best kind of people, bringing light wherever they preach the Dhamma.

Those who give gifts such as food, shelter, medicine, and clothing to the whole Noble Sangha, have given their gifts correctly, have made their offerings correctly, and have made their sacrifice correctly. Those gifts are very beneficial and are praised by the Supreme Buddha, the Knower of the World.

People should always recollect the gifts they have given to the Noble Sangha. This will bring them happiness. They should completely remove the stain of stinginess. Then they can be born in heaven and be praised by the wise."

The moral of this sutta shows that even anumodana-ing in the good deeds of others is by itself a powerful kamma (action) that can ripen and cause us to be reborn in heaven, with a splendid celestial mansion and all kinds of pleasures. Your radiance and followers can still outshine most of the other devas. So please do not look down on the power of anumodana. 

Cr. Sutta Translation from 

https://suttafriends.org/sutta/vv4-6/, Mahamevnawa, Polgahawela, Sri Lanka