To be “swift about hearing ” means being attentive not only to what your child says but also to how he or she says it.
لٰكِنَّ مَا يَبْدُو لَكُمْ تَافِهًا يُمْكِنُ أَنْ يَكُونَ بَالِغَ ٱلْأَهَمِّيَّةِ فِي نَظَرِهِمْ .‏