ب ھ لb-h-l
— The lexicographers say the original sense is to let go and leave free (أَبْهَلَ النَّاقَةَabhala an-nāqata = he left the she-camel loose), and in supplication a person entrusts himself to God and leaves himself free.
Form VIII (iftiʿāl) اِبْتَهَلَ يَبْتَهِلُ اِبْتِهَالًاibtahala yabtahilu ibtihālan: to pray imploringly, to entreat with complete devotion; hence the term «mubāhalah». Only once in the Quran: ﴿ثُمَّ نَبْتَهِلْ فَنَجْعَلْ لَّعْنَتَ اللّٰهِ عَلَي الْكٰذِبِيْنَ﴾ (Āl ʿImrān 3:61)