Yahya ibn Mu’adh said:
“What an evil friend! The one who you have to tell him: ‘Make du’a for me.'”
‘
Yes Wallaahi. From the rights of friendship true friendship is to make du’a for each other for what is good.
Adding on that, there is great reward for doing so, look at this:
Safwan ibn ‘Abdullah ibn Safwan, who was married to Dardaa -the daughter of Abu’d-Darda’- said: “I visited them in Sham and found Umm Dardaa in the house, but not Abu Darda.
She asked: ‘Are you intending to go on hajj this year?’
I replied: ‘Yes.’
So she said, ‘Make du’a to Allah and ask for good for us. For surely The Prophet (sallahAllaahu alayhi wasallam) used to say: “The supplication of a Muslim for his absent brother is answered. At his head there is an appointed angel, whenever he makes du’a to Allah to give his brother good, the angel says: ‘Ameen, and may you have the same.'”‘
[Safwan says]: I then met Abu Dardaa in the market and he said similar to that, relating it from the Prophet (sallahAllaahu alayhi wasallam).”
(Graded Saheeh by Al-Albaani in Saheeh Aadabul Mufrad of al-Bukhaari)
Let’s be good friends from today.
A Benefit A Day Keeps Ignorance Away 
JazakAllah.. What a great reminder!