All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
Loving good for other believers is like loving oneself; it is obligatory in general. Ibn Rajab said in Fat'h Al-Baari:
“A man loves for his brother what he loves for himself if his heart is sound and free of envy, malice, cheating, and hatred. And this is obligatory, as the Prophet said: “You will not enter Jannah (Paradise) until you believe, and you shall not believe until you love one another.” Thus, a believer is the brother of another believer. He wishes for his brother what he wishes for himself of goodness, and he is saddened when his brother is sad.” [End of quote]
The most correct opinion - Allah knows best - is that this matter includes both matters of religion and this world and that it does not contradict the competition for religious good deeds. Some scholars have stated that what is meant is that he loves for others what he loves for himself if he does not compete with them in the same matter. As for competition in matters of religion, there is no objection to competition in pursuit of the best and excellence, with his heart being sound towards Muslims and loving good for them. Al-Nawawi mentioned something similar in his Sharh on Sahih Muslim.
Moreover, Ibn Rajab said in Jame' Al-Uloom Wal-Hikam:
“What is enjoined in Sharee'ah is that he wishes that they be like him. Nevertheless, if someone is better than him in a religious virtue, he should strive to catch up with him and feels sad over his own shortcomings and his failure to catch up with the forerunners in good deeds, not out of envy for what Allah has bestowed upon them, but rather in competition with them.” [End of quote]
Allah knows best.