Surah 17. Al-Israa, Ayah 28

I.e., "because thou art thyself in want, and therefore unable to help others".

You may have to "turn away" from people for two reasons. (1) You may not have the wherewithal with which to entertain them and give them their rights; or (2) you may have to give them a wide berth because their thoughts are not as your thoughts. In either case there is no need to speak harshly to them. Your words should be those of "easy kindness", i.e., the sort of kindness (not merely frigid politeness) which flows from pity and understanding and smooths over unnecessary difficulties in human intercourse.