That is the glad tiding Allah gives to His servants who believed and do righteous deeds; you say: I do not ask any reward upon it except the love for being close relatives, and whoever earns a good, We would increase good for him in it, indeed Allah is oft forgiving, the most appreciative.
It is told in verses 26: 214-215 that you should warn with Adhikr the most kindred, and you should lower your wings to those who follow you from the believers. Accepting the command of this verse when Messenger Muhammed warned with Adhikr his people, he had to face great opposition from them. Just like that the believer today when warns the close relatives, he should also have to face great opposition from his close relatives. Then he is commanded to say them: I do not ask any reward from you for conveying the Message of Allah except the relation of love under the light of Adhikr. See explanation 9: 10; 25: 57, and 43: 67.