Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
suyuti:216aʿUbādah b. al-Ṣāmit

“Ramadan has come to you, a month of blessing in which Allah covers you with goodness: for He sends down Mercy, decreases the sins and answers the duʿās (supplications). ˹During this month˺ Allah audits the competition between you ˹for good deeds˺ and boasts about you to His angels. Thus, show goodness from yourselves to Allah, for it is ˹only˺ the the unfortunate one who would be deprived from the Mercy of Allah ﷻ.”  

Ṭabarānī; Ibn Najjār from ʿUbādah b. al-Ṣāmit. It has Muḥammad b. al-Qays and I could not locate his biography.
السيوطي:٢١٦aعن عُبادةَ بن الصامِت

«أتاكُم شهرُ رمضانَ شهرُ بركة، فيه خيرٌ يُغشَّيكم اللهُ، فَينْزلُ الرحمةَ ويحط فيه الخطأ، ويستجيبُ فيه الدعاء، ينظر اللهُ إلى تنافسكِمْ ويباهى بِكْم ملائكته، فأرُوا الله من أنفسِكمْ خْيرًا، فإنَّ الشِقَىَّ مَنْ حُرِمَ رَحمةَ اللهِ ﷻ۔»  

[طب] الطبرانى في الكبير وابن النجار عن عُبادةَ بن الصامِت (وفيه محمد بن القْيس لم أجد من ترجمه)