bù​dàn​qí​fán

not to spare any pains

Senses

不惮其烦/ 不憚其煩 bù​dàn​qí​fán (also bú​dàn​qí​fán) not to spare any pains

not to mind taking the trouble to do something; to be very patient and undeterred by difficulties or complexity

References

antonym 不惮其烦/不憚其煩 → 不胜其烦/不勝其煩