In plain words
A gift given at an improper place or time, to unworthy recipients, without respect and with contempt, is declared tāmasa.
Word for word
The dāna that is given at a wrong place and time and to unworthy recipients, without honour, with contempt: that is declared tāmasa.
अदेशकाले यद् दानम् अपात्रेभ्यश्च दीयतेअसत्कृतमवज्ञातं तत् तामसमुदाहृतम्
Other commentaries
The commentators
▸Bhagavadgītābhāṣyam· bhāṣya
अदेशकाले अदेशे अपुण्यदेशे म्लेच्छाशुच्यादिसङ्कीर्णे अकाले पुण्यहेतुत्वेन अप्रख्याते सङ्क्रान्त्यादिविशेषरहिते अपात्रेभ्यश्च मूर्खतस्करादिभ्यः, देशादिसम्पत्तौ वा असत्कृतं प्रियवचनपादप्रक्षालनपूजादिरहितम् अवज्ञातं पात्रपरिभवयुक्तं च यत् दानम् , तत् तामसम् उदाहृतम् ॥ २२ ॥
In plain words
'Wrong place and time' -- 'wrong place' means an unholy place, contaminated by outcastes and impurity and the like; 'wrong time' means one with no reputation for merit at all, lacking any special occasion like a solstice. And given to the wrong people -- to fools, to thieves, and such -- or even when the right place and time are available, given without any honor, without a kind word, without washing the recipient's feet, without any real reverence, given with contempt, with open disdain for the one receiving it -- any gift like that is what is meant by tamasic.
Close to the Sanskrit
'Adesakala' -- 'adesa' [means] an impure place, contaminated with barbarians, impurity, and so on; 'akala' [means] not celebrated by reason of being a cause of merit, devoid of any special [occasion] such as a solstice etc.; and to unworthy recipients -- to fools, thieves, and so on -- or [given] when there is abundance of [proper] place etc. -- [a gift which is] disrespectfully [given], devoid of kind words, washing of feet, honoring, and so on, treated with contempt, accompanied by disdain for the recipient -- whatever gift is such, that is declared [to be] tamasic.