According to rahyafte (the missionaries and converts website)Imam al-Rida peace be upon him says:
مَن لَم يَخَفِ اللَّهَ في القَليلِ لَم يَخَفْهُ في الكَثير.
‘Whoever does not fear Allah with regards to small matters will not fear Allah with regards to large matters.’
Source: Bihar al-Anwar, v. 71, p. 174, no. 10