The equality of all human beings, races and nations before Allah is highlighted in verse 11 of Surat Al-Hujurat, where Allah says that no race should look down on any other race and that the only thing that places one person above another is, taqwa (consciousness of Allah) and good deeds. This unseen quality that is only known to Allah is what makes you superior before Him. As Nouman Ali Khan explains, the verse singles out women who mock other women and treat them as inferior. Such a societal attitude betrays a spiritual crisis and can even breed hatred, animosity and even war, between nations.
Silence is golden. Islam encourages us to speak what is good and beneficial; at the same time cautioning us to be careful in what we say, lest we say something that is harmful or false. Shaykh Kamal El Mekki talks about this further in this video.