The Quran

۞ وَقَضىٰ رَبُّكَ أَلّا تَعبُدوا إِلّا إِيّاهُ وَبِالوالِدَينِ إِحسانًا ۚ إِمّا يَبلُغَنَّ عِندَكَ الكِبَرَ أَحَدُهُما أَو كِلاهُما فَلا تَقُل لَهُما أُفٍّ وَلا تَنهَرهُما وَقُل لَهُما قَولًا كَريمًا

Muhammad Asad

for thy Sustainer has ordained that you shall worship none but Him. And do good unto [thy] parents.¹ Should one of them, or both, attain to old age in thy care, never say "Ugh"² to them or scold them, but [always] speak unto them with reverent speech,

Whereas God is the real, ultimate cause of man's coming to life, his parents are its outward, immediate cause: and so the preceding call to God is followed by the injunction to honour and cherish one's parents. Beyond this, the whole of the present passage - up to and including verse 39 - is meant to show that kindness and just dealings between man and man are an integral part of the concept of "striving for the good of the life to come"
In Arabic, uff - a word or sound indicative of contempt, dislike or disgust.