In reply to Ronak Bhatt:
realtime v;
(posedge local_clk1) disable iff ((!enable)|(!reset)) (v=$realtime) |-> @(negedge local_clk1) ($realtime-v)==TON_local_clk1;
i wanted check above thing my code but i could not able to sample v = $realtime its showing syntax error as you said , so any other way i can sample the v in my property or any other way i can write my property , because if am not use the disable iff i will get initially assertion error (when enable and is low);