What is the ruling on not helping those who consider the one helping them to be their servant?

A Muslim who helps his brethren seeks the countenance of Allah Almighty and His reward, desiring no recompense or thanks from people, as stated in His saying, the Most High: "We feed you only for the countenance of Allah. We wish not from you reward or gratitude." And whoever is sincere in seeking Allah's pleasure by helping people, he is not harmed by their kindness or their ill-treatment, nor does he abandon helping due to what he might perceive as being considered a servant, for his reward is stored with Allah. If the help is not obligatory, then abandoning it does not entail sin, but rather he misses out on the reward.