إِنif تَطلgrows long مِنكَof yours لِحيةa beard ثمّthen تعوضis replaced (as written; possibly a typo for 'broadens')
إِن تَطل مِنكَ لِحية ثمّ تعوض
كُنتَyou would be خِدنَthe intimate companion of العَقلِthe mind الخَفيفِfrivolous المريضِailing
كُنتَ خِدنَ العَقلِ الخَفيفِ المريضِ
If your beard grows long and is then replaced,
If a beard sprouts from your chin, you've regained
you are the companion of a frivolous, ailing mind.
The feeble mind, the foolish wit you've feigned
مَنwhoever يُرِدْseeks فيamong الوَرىhumankind رَجاحَةَsoundness of عَقلٍmind
مَن يُرِدْ في الوَرى رَجاحَةَ عَقلٍ
عَنهُaway from himself يَتركْlet him leave حَملَthe burden of الطّويلِthe long العَريضِthe broad
عَنهُ يَتركْ حَملَ الطّويلِ العَريضِ
Whoever among mortals seeks sound judgment,
If you want in this world a wise and prudent brain
let him cast off the burden of the long, broad beard.
Abandon carrying burdens big and vain
Sol 6.1