Is it permissible to do good to others and speak kindly to them with the aim of avoiding their ill-treatment and preventing them from hating me, rather than seeking the countenance of God?

Treating colleagues kindly is a good deed that fosters affection and protects against the evil of Satan. Allah has enjoined good speech so that Satan does not sow discord among people, as stated in His verse: "And tell My servants to say that which is best. Indeed, Satan incites [discord] among them." The Sharia encourages responding to evil with good, as stated in His verse: "Repel [evil] with that which is better." One must purify their intention for Allah and seek His pleasure in doing so, to attain the great reward, as stated in His verse: "And whoever does that, seeking the pleasure of Allah, We will surely grant him a great reward." Thus, the complete reward depends on one's intention and sincerity towards Allah.