Rest a LOT unfortunately. Tendon related issues either recover themselves in a couple days to a week (usually), or take 6-8+ weeks of inactivity (less common) to recover. If you jump back into working weights too early it'll just reset the timer again more or less. Couple suggestions for you from guys I train(ed) with, without knowing your routine/history I still feel these might help a bit:
-Add in Dynamic work if you don't do it already. Simply look up Dynamic Effort Method on Youtube and watch how Louie Simmons or various other powerlifters or strength coaches discuss it. The gist of this is that you take something quite light (40-60% of your 1rm on a movement) and focus on hammering it for sets of 1-3 reps with full emphasis on bar speed 2-3x a week. Westside Barbell guys recommend using a band or chain for added resistance at the top but this is not necessary if you're just using the method to help keep things healthy. My personal preference is to do 10 sets of 2 on Bench, 10 sets of 2 on Squats, and 10 singles on deadlifts with ~40% of most recent comp max and I adjust the band tension over three week waves. I've barely raised the weight I use on these over the years but my maxes have all gone up significantly, my gas tank has grown a shit load, my joints feel way better, and aside from a recent freak accident I attribute it to helping me remain injury free. This essentially helps the body learn to activate shit at a fast pace and with maximum force, and a lot of injuries come from people trying to move too fast or with too much force when they're not prepared for it so naturally this is exactly how you'd want to work to fix it.
-Skip the ice and painkillers IF YOU CAN MANAGE IT. Now, if you are in dire pain and can't perform basic everyday life or job tasks without some ibuprofen and a freezing cuff then by all means keep doing them BUT if you lay off these things it'll actually help. Stan Efferding has videos on Youtube which explain it better than I can paraphrase here but the main idea is that inflammation is a bodily process meant to get the brain's attention so it actually starts shoving nutrients toward the area to heal it. If you shut down the inflammation you actually risk prolonging the process! Now, this is not to say if you have a lump the side of a golf ball on your arm you should ignore it of course but if you have no outwardly visible signs of injury and simply feel the pains when you perform certain movements then I highly recommend going the no-ice/no-pill route. Heat seems to be different in that it'll still help, though, but to what extent is pretty unknown. My personal suggestion is just to roll on menthol (Icy Hot, Biofreeze type products) or capsaicin (This doesn't help all cases but might help yours) and maybe put on an elbow sleeve/cuff or wrist brace if manageable. The same sleeves worn for assistance in the gym can be worn out of the gym to help everyday life btw so if you own a pair just wear em daily till the tendons are healed.
-Look at your elbow extension vs flexion movements and see if you have a shocking imbalance. I had minor tendon pains for a bit and realized I actually have to do fucking biceps work. Years of just letting back day build them up because I hate curls, well turns out that can cause issues after a while! There's no magic proportion here but if you're like I was and you do a few hundred extension movements per week but never direct flexion isolations then add in some curls of any variety, or the opposite if you find you do way too much biceps and nowhere near enough triceps.
-Check your shoulders. Like with leg and foot issues beginning at the hip joint sometimes, arm issues can begin at the shoulder joint. If you do a shit load of front laterals consider reducing the volume on those as these seem to be a movement that can really bother the whole arm depending on how you hold the weight, weight amount used, and volume.
Without knowing really anything about the situation surrounding the injury and when/how it occurred I'd also say limit your weight and volume but keep moving if possible during recovery, Even if the best you can manage without pain is to do movements with 5lb dumbbells keep doing them. Find a comfortable weight and throw your ego aside for a while, train the way you'd train if a physical therapist worked with you. So if the pain comes from a specific movement I'd drop the weight as low as necessary to perform that movement without pain but with enough feeling/feedback from the body to know you're working and just do more or less arbitrary sets and reps of it. Then on movements that still involve the arm but do not flare up the pain, train those movements as normal. If this means for example you lay down and do dumbbell bench presses with the 5's for a bit then go hit rope pulldowns with the full stack then so be it! If you need to keep yourself entertained in this time, use these low weight reps to give yourself an opportunity to explore better ways to perform the lift or 'feel' it better. Anything you learn can be applied later when you're back to normal weights and will probably help you progress.