Kevin Thomson has questioned the commitment of Jason Cummings.
The former Hibs striker has only started one SPFL match since moving to Ibrox on loan from Nottingham Forest.
New Forest boss Aitor Karanka quickly decided to send Cummings out on loan with the 22-year-old having to settle for watching Alfredo Morelos from the bench.
Thomson recently took up a part-time coaching role at Ibrox and has warned his former team-mate that there are no short cuts to success.
Speaking to The Sun about Cummings Thomson said: “The first time I saw Jason when he first came in here, Jason Holt and him were in the car park at 2pm. I said to them ‘It’s 2pm, where are you going?’.
“I said ‘You should be in there, practising’. Jason replied ‘I’ve got a game tomorrow, Uncle T’. I said ‘But you should be in there getting better’.
“I told Jason that Rangers was an amazing club and I said that these next few months he should be as selfish as he can be to showcase his talents here, to hopefully be here long-term.
“When I was a player at Rangers I was lucky that Walter Smith told me that being OK at this club wasn’t good enough.”
Despite his dedication to the game Thomson retired at the age of 32 after a third spell at Hibs playing in The Championship.
Cummings is one of four loan signings at Ibrox that will leave Graeme Murty’s squad short on numbers at the end of the season.
With Kenny Miller and David Bates still to be offered new contracts the Ibrox club are facing an end of season clear out although Andy Halliday is under contract until 2020.
The recent £3m loan from Close Brothers, plus charges will have to be repaid before Murty is able to enter the transfer market.