Does an inner struggle with holding back affect the reward of charity (ṣadaqah) or zakat?

What you feel of hesitation and inner struggle regarding charity is from Satan, to deprive you of its reward. Satan promises you poverty to frighten you, so you withhold what you possess. Freedom from covetousness and stinginess is a sign of success. Therefore, seek refuge with Allah from Satan and strive against yourself to give charity. The hesitation you feel does not diminish your reward, but rather increases it, because striving against oneself in obedience is something for which a Muslim is rewarded.