Hakeemul Ummat Hazrat Moulana Shah Ashraf Ali Thanvi ra writes in Qasdus Sabil ila Mawla al-Jalil, a primer for those involved in tasawwuf and islah;
“Few of the sins are in particular extremely destructive for those traversing the sulook (spiritual path). They include:
1. Riya (ostentation/show off)
2. Takabbur (Arrogance)
3. Useless and sinful talking
4. Looking lustfully at ghair-mahram females and (young/adolescent) boys
5. Being angry inappropriately and/or excessively”
Tasheel Qasdus Sabil, page 25 & 26, by Hazrat Mawlana Shah Lutufe Rasool sahib ra (senior khalifa of Hazrat Hakeemul Ummat ra).