Tafsir of Al-Anbiya' 21:19

وله من في السماوات واﻻرض ومن عنده

To Him belongs whosoever is in the heavens and on earth. And those who are near Him i.e., the angels,

ﻻ يستكبرون عن عبادته

are not too proud to worship Him, they do not feel proud and do not refuse to worship Him. This is like the Ayah:

لن يستنكف المسيح أن يكون عبدا لله وﻻ المليكة المقربون ومن يستنكف عن عبادته ويستكبر فسيحشرهم إليه جميعا

Al-Masih will never be proud to reject being a servant of Allah, nor the angels who are the near. And whosoever rejects His worship and is proud, then He will gather them all together unto Himself. (4:172)

وﻻ يستحسرون

nor are they weary. means, they do not get tired or feel bored

يسبحون الليل والنهار ﻻ يفترون