Literary and usually bound: 仗恃 / 依恃 (to rely on), and the set phrase 有恃无恐 (to feel safe with backing). It carries a negative tone of leaning on something to act arrogantly.
Left-side heart radical 忄, the upright form of 心. Relying on something is a mental attitude, so the heart radical fits the 'depend on, count on' sense of 恃.
